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In: Computers and Technology

Submitted By jayson2555
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Pages 187
Chapter 1: Introduction to Computer Networks and Data Communications
TRUE/FALSE
1.
Data is information that has been translated into a form that is more conducive to storage, transmission, and calculation.
ANS: T
2.
ANS: F

PTS: 1
Some people call computer terminals thick-client workstations.
PTS: 1

3.
A type of microcomputer-to-local area network connection that is growing in popularity is the wireless connection.
ANS: T

PTS: 1

4.
To communicate with the Internet using a dial-up modem, a user’s computer must connect to another computer that is already communicating with the Internet.
ANS: T

PTS: 1

5.
It is not possible to connect two local area networks so that they can share peripherals as well as software.
ANS: F

PTS: 1

6.
Metropolitan area networks can transfer data at fast, LAN speeds but over smaller geographic regions than typically associated with a local area network.
ANS: F
7.
ANS: T
8.
networks.
ANS: T
9.
ANS: F

PTS: 1
The Internet is not a single network but a collection of thousands of networks.
PTS: 1
One of the most explosive areas of growth in recent years has been cellular phone
PTS: 1
By the 1970s, telephone systems carried more computer data than voice.
PTS: 1

10.
Network architectures are cohesive layers of protocols defining a set of communication services.
ANS: T

PTS: 1

11.
The OSI model tells us what kind of wire or what kind of connector to use to connect the pieces of a network.
ANS: F
12.
ANS: F points. 13.

ANS: T
14.
ANS: F
15.
software.
ANS: T
16.
ANS: T
17.
ANS: T
18.
ANS: F
19.
ANS: T

PTS: 1
The application layer of the OSI model is responsible for token management.
PTS: 1
The session layer of the OSI model is responsible for establishing synchronization
PTS: 1
The network layer of the OSI model is an end-to-end layer.
PTS: 1
The data link layer of the OSI model can incorporate some form of error detection
PTS: 1
The TCP/IP protocol suite does not have rigidly defined layers as the OSI model does.
PTS: 1
Telnet is used to allow a remote user to log in to another computer system.
PTS: 1
SNMP is used to allow users to send and receive electronic mail.
PTS: 1
The lowest layer of the TCP/IP protocol suite is the network access or physcial layer.
PTS: 1

20.
In a network architecture, as the packet moves up through the layers, the data packet shrinks in size.
ANS: T

PTS: 1

MULTIPLE CHOICE
1.
A ____ is an interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areas.
a.

personal area network
(PAN)

c.

wireless network

b.

computer network

d.

local area network (LAN)

ANS: B

PTS: 1

a.

2.
____ is the transmission of multiple signals on one medium.
Multiplexing
c.
Modem

b.

Codec

d.

ANS: A
3.
software.

Package

PTS: 1
____ is the design, installation, and support of a network and its hardware and

a.

Convergence

c.

Data network

b.

Voice network

d.

Network management

ANS: D
4.

PTS: 1
____ are the computers that store network software and shared or private user files.

a.

Switches

c.

Servers

b.

Routers

d.

Hubs

ANS: C
5.

PTS: 1
____ are capable of filtering out unnecessary traffic.

a.

Switches

c.

Servers

b.

Routers

d.

Workstations

ANS: A

PTS: 1

6.
A ____ is a device that is essentially a keyboard and screen with no long-term storage capabilities and little, if any, processing power.
a.

protocol

c.

thick-client

b.

mainframe

d.

computer terminal

ANS: D

PTS: 1

7.
In a(n) ____ system, a user at a microcomputer, or client machine, issues a request for some form of data or service.
a.

wireless

c.

bridge

b.

client/server

d.

Internet

ANS: B
____.
a.

8.

PTS: 1
A modem and a dial-up telephone service provides data transfer rates of approximately

56,000 bits per second
(56 kbps)

c.

128,000 bits per second (128 kbps)

b.

112,000 bits per second
(112 kbps)

ANS: A
9.

d.

256,000 bits per second (256 kbps)

PTS: 1
The Internet “talks” only ____, so users must use software that supports this protocol.

a.

IPX/SPX

c.

TCP/IP

b.

DSL

d.

FTP

ANS: C
10.

PTS: 1
The devices that usually connect two or more LANs are the switch, hub, and ____.

a.

workstation

c.

server

b.

access point

d.

router

ANS: D
11.

PTS: 1
The personal area network was created in the late ____.

a.

1970s

c.

1990s

b.

1980s

d.

2000s

ANS: C

PTS: 1

12.
A ____ is a high-speed network that interconnects multiple sites within a close geographic region, such as a large urban area.
a.

metropolitan area network (MAN)

c.

local area network (LAN)

b.

wide area network
(WAN)

d.

personal area network (PAN)

ANS: A
13.

PTS: 1
Connecting two wide area networks requires devices such as high-speed ____.

a.

hubs

c.

bridges

b.

routers

d.

reflectors

ANS: B

PTS: 1

14.
The ____ in a network architecture define a model for the functions or services that need to be performed.
a.

servers

c.

routers

b.

workstations

d.

layers

ANS: D

PTS: 1

15.
The International Organization for Standardization (ISO) created the ____ reference model in an attempt to standardize the design of communication systems and the interoperability between their components.

a.

Open Systems
Interconnection (OSI)

c.

FTP

b.

TCP/IP

d.

ASCII

ANS: A

PTS: 1

16.
The ____ layer of the OSI model makes sure the data received at the very end of a transmission is exactly the same as the data originally transmitted.
a.

application

c.

transport

b.

session

d.

network access

ANS: C

PTS: 1

17.
The ____ layer of the OSI model performs a series of miscellaneous functions necessary for presenting the data package properly to the sender or receiver.
a.

transport

c.

applications

b.

presentation

d.

session

ANS: B
18.
management.

PTS: 1
The ____ layer is responsible for establishing sessions between users for token

a.

network

c.

transport

b.

application

d.

session

ANS: D

PTS: 1

19.
____ is a service that controls which user’s computer talks when during the current session by passing a software token back and forth.
a.

Token management

c.

Character conversion

b.

Synchronization point

d.

Encryption/decryption

ANS: A
20.
flow control.

PTS: 1
The ____ layer of the OSI model performs end-to-end error control and end-to-end

a.

application

c.

transport

b.

presentation

d.

session

ANS: C
21.

PTS: 1
The ____ layer of the OSI model performs congestion control.

a.

network

c.

physical

b.

data link

d.

session

ANS: A
22.

PTS: 1
____ ensures that the network does not become saturated at any one point.

a.

End-to-end error control

c.

End-to-end flow control

b.

Congestion control

d.

Synchronization points control

ANS: B

PTS: 1

23.
The bottom layer in the OSI model—the ____ layer—handles the transmission of bits over a communications channel.
a.

data link

c.

physical

b.

application

d.

network

ANS: C

PTS: 1

24.
The ____ suite was not created by a standards-making organization but by a group of computer scientists.
a.

OSI model

c.

OSI model

b.

FTP protocol

d.

TCP/IP protocol

ANS: D
25.
services.

PTS: 1
The TCP/IP ____ layer supports network applications and may include presentation

a.

transport

c.

network

b.

application

d.

network access

ANS: B

PTS: 1

26.
____ is used to allow the numerous elements within a computer network to be managed from a single point.
a.

Simple Network Management Protocol (SNMP)

b.

Simple Mail Transfer Protocol (SMTP)

c.

Telnet

d.

File Transfer Protocol (FTP)

ANS: A

PTS: 1

27.
The TCP/IP ____ layer commonly uses the Transmission Control Protocol (TCP) to maintain an error-free end-to-end connection.
a.

network

c.

transport

b.

network access

d.

application

ANS: C

PTS: 1

28.
The TCP/IP ____ layer, sometimes called the Internet layer, is roughly equivalent to
OSI’s network layer.
a.

network access

c.

transport

b.

application

d.

network

ANS: D

PTS: 1

29.
A(n) ____ connection is a nonphysical connection between sender and receiver that allows an exchange of commands and responses.
a.
physical
c.
real
b.

encapsulated

ANS: D
____.

30.

d.

logical

PTS: 1
The addition of control information to a packet as it moves through the layers is called

a.

encapsulation

c.

payload

b.

overloading

d.

filtering

ANS: A
31.

PTS: 1
The merging together of two or more businesses or technologies is termed

a.

convergence

c.

manipulation

b.

inversion

d.

commercilization

ANS: A

PTS: 1

COMPLETION
1.
Computer networks that use radio waves are termed ____________________ and can involve broadcast radio, microwaves, or satellite transmissions.
ANS: wireless
PTS: 1 reside. 2.

____________________ are personal computers or microcomputers where users

ANS: Workstations
PTS: 1
3.

____________________ are sets of rules used by communication devices.

ANS: Protocols
PTS: 1
4.
Metropolitan area networks are a cross between local area networks and
____________________ networks.
ANS: wide area
PTS: 1

5. network data.

A(n) ____________________ converts the local area network data into wide area

ANS: router
PTS: 1
6.
In a(n) ______________________________ connection, the action of a person or object triggers a sensor that is connected to a network.
ANS: sensor-to-local area network
PTS: 1
7.
A dictionary might define “____________________” as the process of coming together toward single point.
ANS: convergence
PTS: 1
8.
A(n) ____________________, or communications model, places the appropriate network pieces in layers.
ANS: network architecture
PTS: 1
9.
The two most common architectures known today are the Open Systems
Interconnection (OSI) model and the ____________________ protocol suite.
ANS: TCP/IP
PTS: 1
10.
The OSI model consists of seven layers: application, presentation, session,
____________________, network, data link, and physical.
ANS: transport
PTS: 1
11.
The top layer in the OSI model is the ____________________ layer, where the application using the network resides.
ANS: application
PTS: 1
12.
The ____________________ layer of the OSI model is responsible for establishing sessions between users.

ANS: session
PTS: 1 failures. 13.

_________________________ are backup points that are used in case of errors or

ANS: Synchronization points
PTS: 1
14.
The ____________________ layer of the OSI model is responsible for creating, maintaining, and ending network connections.
ANS: network
PTS: 1
15.
The ____________________ layer of the OSI model is responsible for taking data from the network layer and transforming it into a cohesive unit called a frame.
ANS: data link
PTS: 1
16.
The ____________________ protocol suite incorporates the TCP and IP protocols and has in fact always been more popular than the OSI model.
ANS: TCP/IP
PTS: 1
17.
______________________________ is used to transfer files from one computer system to another.
ANS:
File Transfer Protocol (FTP)
File Transfer Protocol
FTP
PTS: 1
18.
___________________________________ is used to allow Web browsers and servers to send and receive World Wide Web pages.
ANS:
Hypertext Transfer Protocol (HTTP)
Hypertext Transfer Protocol
HTTP
PTS: 1

19.
The _________________________ is the software that prepares a packet of data so that it can move from one network to another on the Internet or within a set of corporate networks.
ANS:
Internet Protocol
Internet Protocol (IP)
IP
PTS: 1
20.
The ____________________ connection is the only direct connection between sender and receiver and is at the physical layer, where actual 1s and 0s are transmitted over wires or airwaves.
ANS: physical
PTS: 1
21.
The ______________ layer of the TCP/IP protocol suite is responsible for making sure that what leaves one end of the network arrives at the other end of the network exactly the same.
ANS: transport
PTS: 1
ESSAY
1.

What is data communications?

ANS:
We will define data communications as the transfer of digital or analog data using digital or analog signals. Once created, these analog and digital signals then are transmitted over conducted media or wireless media. Both the data and the signal can be analog or digital, allowing for four possible combinations. Transmitting analog data by analog signals and digital data by digital signals are fairly straightforward processes—the conversion from one form to another is relatively simple. Transmitting digital data using analog signals, however, requires the digital data to be modulated onto an analog signal, which is what happens with a modem and the telephone system. Transmitting analog data using digital signals requires the data to be sampled at specific intervals and then digitized into a digital signal, which is what happens with a device called a digitizer, or codec.
PTS: 1
2.

What are the components of a wide area network?

ANS:
Wide area networks also can be of many types. Although many different technologies are used to support wide area networks, all wide area networks include the following components:
* Nodes, which are the computing devices that allow workstations to connect to the network and that make the decisions about where to route a piece of data
* Some type of high-speed transmission line, which runs from one node to another
* A sub-network, which consists of the nodes and transmission lines, collected into a cohesive unit
PTS: 1

3.

What are the benefits of a microcomputer-to-local area network connection?

ANS:
Perhaps the most common network connection today, the microcomputer-to-local area network (LAN) connection is found in virtually every business and academic environment—and even in many homes.
The LAN is an excellent tool for sharing software and peripherals. In some LANs, application software, such as project management or spreadsheet software, resides on a central computer called a server. Using microcomputers connected to a LAN, end users can request and download an application, then execute it on their computers. If users wish to print documents on a high-quality network printer, the LAN contains the network software necessary to route their print requests to the appropriate printer. If users wish to access their e-mail from the corporate e-mail server, the local area network provides a fast, stable connection between user workstations and the e-mail server.
PTS: 1
4.

Explain what is meant by personal area network-to-workstation connections.

ANS:
The personal area network was created in the late 1990s and is one of the newer forms of computer networks. Using wireless transmissions with devices such as personal digital assistants (PDAs), laptop computers, and portable music players, an individual can transfer voice, data, and music from handheld devices to other devices such as microcomputer workstations. Likewise, a user can download data from a workstation to one of these portable devices. For example, a user may use a PDA to record notes during a meeting. Once the meeting is over, the user can transmit the notes over a wireless connection from the PDA to his or her workstation. The workstation then runs a word processor to clean up the notes, and the formatted notes are uploaded to a local area network for corporate dissemination. PTS: 1
5.

Briefly explain some examples of convergence in the wireless market.

ANS:
Today we see many different examples of convergence, particularly in the wireless markets. For example, it is now quite common to snap a photo using a cell phone and then transfer the image over the cell phone network to another cell phone. Shortly after the introduction of photo-enabled cell phones, cell phones also became capable of sending and receiving instant messages. Then in 2005, cell phone providers started offering services that allow a user to transmit high-speed data over a cell phone connection. These all are examples of the convergence of two different applications (for example, digital photography and cell phones in the case of photo-enabled cell phones) into a single technology. PTS: 1

Chapter 2: Fundamentals of Data and Signals
TRUE/FALSE
1.

The terms “data” and “signal” mean the same thing.

ANS: F

PTS: 1

2.
By convention, the minimum and maximum values of analog data and signals are presented as voltages.
ANS: T

PTS: 1

3.
One of the primary shortcomings of analog data and analog signals is how difficult it is to separate noise from the original waveform.
ANS: T

PTS: 1

4.
The ability to separate noise from a digital waveform is one of the great strengths of digital systems.
ANS: T
5.
ANS: T
6.
frequency).
ANS: T
7.
ANS: F

PTS: 1
A sine wave is used to represent an analog signal.
PTS: 1
The period of a signal can be calculated by taking the reciprocal of the frequency (1/
PTS: 1
The telephone system transmits signals in the range of 150 Hz to 1500 Hz.
PTS: 1

8.
Attenuation in a medium such as copper wire is a logarithmic loss and is a function of distance and the resistance within the wire.
ANS: T
9.
ANS: T

PTS: 1
Like signals, data can be analog or digital.
PTS: 1

10.
Telephones, AM radio, FM radio, broadcast television, and cable television are the most common examples of analog data-to-digital signal conversion.
ANS: F
11.
hardware.
ANS: T

PTS: 1
The NRZ-L encoding scheme is simple to generate and inexpensive to implement in
PTS: 1

12.
With NRZI, the receiver has to check the voltage level for each bit to determine whether the bit is a 0 or a 1.

ANS: F

PTS: 1

13.
With NRZ-L, the receiver has to check whether there is a change at the beginning of the bit to determine if it is a 0 or a 1.
ANS: F

PTS: 1

14.
An inherent problem with the NRZ-L and NRZI digital encoding schemes is that long sequences of 0s in the data produce a signal that never changes.
ANS: T

PTS: 1

15.
The big disadvantage of the Manchester schemes is that roughly half the time there will be two transitions during each bit.
ANS: T

PTS: 1

16.
Under some circumstances, the baud rate may equal the bps, such as in the
Manchester encoding schemes.
ANS: F high. 17.

ANS: F

PTS: 1
Amplitude shift keying is restricted to only two possible amplitude levels: low and
PTS: 1

18.
Amplitude shift keying is susceptible to sudden noise impulses such as the static charges created by a lightning storm.
ANS: T data. 19.

ANS: F

PTS: 1
Frequency shift keying is susceptible to sudden noise spikes that can cause loss of
PTS: 1

20.
Phase changes are not affected by amplitude changes, nor are they affected by intermodulation distortions.
ANS: T
21.
the baud rate.
ANS: F

PTS: 1
The bps of the data transmitted using quadrature amplitude modulation is four times
PTS: 1

22.
According to a famous communications theorem created by Nyquist, the sampling rate using pulse code modulation must be at least three times the highest frequency of the original analog waveform. ANS: F

PTS: 1

23.
One of the most common forms of data transmitted between a transmitter and a receiver is textual data.
ANS: T

PTS: 1

24.
Certain control characters provide data transfer control between a computer source and computer destination.
ANS: T
25.
ANS: T
26.
ANS: F
27.
ANS: T

PTS: 1
IBM mainframe computers are major users of the EBCDIC character set.
PTS: 1
ASCII is a data code rarely used in the world.
PTS: 1
A byte consists of 8 bits.
PTS: 1

28.
One of the major problems with Unicode is that it cannot represent symbols other than those found in the English language.
ANS: F
29.
ANS: T
0010.

30.

ANS: F

PTS: 1
ASCII is one of the supported code charts in Unicode.
PTS: 1
In Unicode, the letter “r” is represented by the binary value of 0000 0000 0101 0100
PTS: 1

MULTIPLE CHOICE
1.

____ is entities that convey meaning within a computer or computer system.

a.

Signals

c.

Impulse

b.

Data

d.

EMI

ANS: B

PTS: 1

2.
If you want to transfer data from one point to another, either via a physical wire or through radio waves, the data has to be converted into a(n) ____.
a.

hertz

c.

signal

b.

Unicode

d.

byte

ANS: C

PTS: 1

3.
____ are represented as continuous waveforms that can be at an infinite number of points between some given minimum and maximum.
a.
Analog signals
c.
Digital data
b.

Digital signals

ANS: A
4.

d.

Digital pulses

PTS: 1
The most common example of ____ data is the human voice.

a.

sampling

c.

digital

b.

baud

d.

analog

ANS: D

PTS: 1

5.
Unfortunately, noise itself occurs as a(n) ____ waveform, and this makes it challenging, if not extremely difficult, to separate noise from an analog waveform that represents data.
a.

analog

c.

hertz

b.

digital

d.

byte

ANS: A
6.

PTS: 1
____ are discrete waveforms, rather than continuous waveforms.

a.

Analog signals

c.

Digital signals

b.

Analog bauds

d.

Analog data

ANS: C
7.
and ____.

PTS: 1
The three basic components of analog and digital signals are: amplitude, frequency,

a.

cycles

c.

hertz

b.

baud

d.

phase

ANS: D
8.

PTS: 1
The amplitude of a signal can be expressed as volts, ____, or watts.

a.

hertz

c.

bits

b.

amps

d.

bytes

ANS: B

PTS: 1

9.
The ____ of a signal is the number of times a signal makes a complete cycle within a given time frame.
a.

phase

c.

period

b.

amplitude

d.

frequency

ANS: D

PTS: 1

a.

10. bytes b.

Cycles per second, or frequency, is represented by ____.
c.
bits

hertz

d.

ANS: B

watts

PTS: 1

11.
The frequency range of the average human voice usually goes no lower than 300 Hz and no higher than approximately ____ Hz.
a.

2200

c.

3400

b.

2400

d.

5300

ANS: C
12.
4200 Hz.

PTS: 1
The lowest note possible on the piano is ____ Hz, and the highest note possible is

a.

30

c.

300

b.

80

d.

450

ANS: A

PTS: 1

13.
The bandwidth of a telephone system that transmits a single voice in the range of 300
Hz to 3400 Hz is ____ Hz.
a.

10

c.

3100

b.

100

d.

3700

ANS: C

PTS: 1

14.
When traveling through any type of medium, a signal always experiences some loss of its power due to friction. This loss of power, or loss of signal strength, is called ____.
a.

amplification

c.

decibel

b.

friction

d.

attenuation

ANS: D
15.

PTS: 1
When a signal is amplified by an amplifier, the signal gains in ____.

a.

decibels

c.

bytes

b.

hertz

d.

watts

ANS: A

PTS: 1

16.
____ is the process of sending data over a signal by varying either its amplitude, frequency, or phase.
a.

Amplification

c.

Attenuation

b.

Modulation

d.

Digital encoding

ANS: B

PTS: 1

17.
The ____ encoding scheme has a voltage change at the beginning of a 1 and no voltage change at the beginning of a 0.
a.
nonreturn to zero inverted
c.
Manchester
(NRZI)
b.

nonreturn to zero-level
(NRZ-L)

ANS: A

d.

Differential Manchester

PTS: 1

18.
The ____ digital encoding scheme is similar to the Manchester scheme in that there is always a transition in the middle of the interval.
a.

NRZ-L

c.

differential Manchester

b.

Bipolar-AMI

d.

NRZI

ANS: C

PTS: 1

19.
The Manchester encoding schemes are called ____, because the occurrence of a regular transition is similar to seconds ticking on a clock.
a.

continuous-clocking

c.

discrete-clocking

b.

analog-clocking

d.

self-clocking

ANS: D
20.

PTS: 1
The number of times a signal changes value per second is called the ____ rate.

a.

hertz

c.

watts

b.

baud

d.

volts

ANS: B
21.

PTS: 1
The data rate is measured in ____.

a.

bits per second (bps)

c.

bauds per second (bps)

b.

bytes per second (Bps)

d.

hertz per second (hps)

ANS: A

PTS: 1

22.
Using ____, when a device transmits a binary 0, a zero voltage is transmitted. When the device transmits a binary 1, either a positive voltage or a negative voltage is transmitted.
a.

Manchester

c.

differential Manchester

b.

bipolar-AMI

d.

NRZ-L

ANS: B

PTS: 1

23.
The primary advantage of a bipolar scheme is that when all the voltages are added together after a long transmission, there should be a total voltage of ____.
a.

-2

c.

0

b.

-1

d.

1

ANS: C

PTS: 1

24.
The Manchester encoding schemes solve the synchronization problem but are relatively inefficient because they have a baud rate that is ____ the bps.
a.
equal to
c.
three times
b.

twice

d.

ANS: B

four times

PTS: 1

25.
A device that modulates digital data onto an analog signal and then demodulates the analog signal back to digital data is a ____.
a.

repeater

c.

hub

b.

switch

d.

modem

ANS: D

PTS: 1

26.
Three currently popular modulation techniques for encoding digital data and transmitting it over analog signals are amplitude shift keying, frequency shift keying, and ____ shift keying. a.

noise

c.

strength

b.

baud

d.

phase

ANS: D
27.

PTS: 1
The simplest modulation technique is ____ shift keying.

a.

amplitude

c.

frequency

b.

phase

d.

noise

ANS: A
28.

PTS: 1
Frequency shift keying is subject to ____.

a.

baud noise

c.

intermodulation distortion

b.

bps distortion

d.

noise spikes

ANS: C
29.
waveform.

PTS: 1
____ shift keying represents 0s and 1s by different changes in the phase of a

a.

Amplitude

c.

Frequency

b.

Phase

d.

Noise

ANS: B bits. 30.

PTS: 1
____ shift keying incorporates four different phase angles, each of which represents 2

a.

Quadrature amplitude

c.

Quadrature noise

b.

Quadrature frequency

d.

Quadrature phase

ANS: D

PTS: 1

31.
____ modulation, which is commonly employed in contemporary modems, uses each signal change to represent 4 bits.
a.
Quadrature amplitude
c.
Quadrature noise
b.

Quadrature frequency

ANS: A
32.

d.

Quadrature phase

PTS: 1
One encoding technique that converts analog data to a digital signal is ____.

a.

NRZ-L

c.

pulse code modulation (PCM)

b.

Manchester

d.

NRZ-I

ANS: C

PTS: 1

33.
Tracking an analog waveform and converting it to pulses that represent the wave’s height above (or below) a threshold is termed ____.
a.

pulse amplitude modulation (PAM)

c.

quantization

b.

codec

d.

quantization levels

ANS: A

PTS: 1

34.
When converting analog data to digital signals, the frequency at which the snapshots are taken is called the ____ rate.
a.

baud

c.

bps

b.

sampling

d.

byte

ANS: B
35.

PTS: 1
With ____, a codec tracks the incoming analog data by assessing up or down “steps.”

a.

differential Manchester

c.

NRZI

b.

Bipolar-AMI

d.

delta modulation

ANS: D
36.

PTS: 1
Three important data codes are EBCDIC, ____, and Unicode.

a.

NRZ-L

c.

ASCII

b.

4B/5B

d.

NRZI

ANS: C
37.

PTS: 1
____ is an 8-bit code allowing 256 possible combinations of textual symbols.

a.

EBCDIC

c.

NRZI

b.

Unicode

d.

UTF-9

ANS: A

PTS: 1

a.

38.
The ____ is a government standard in the United States.
UTF-8

b.

EBCDIC

c.

American Standard Code for Information Interchange (ASCII)

d.

Unicode

ANS: C

PTS: 1

39.
The ASCII character set exists in a few different forms, including a ____ version that allows for 128 possible combinations of textual symbols.
a.

3-bit

c.

6-bit

b.

5-bit

d.

7-bit

ANS: D
40.

PTS: 1
The Greek symbol β has the Unicode value of hexadecimal ____.

a.

01F3

c.

5.00E+04

b.

03B2

d.

C108

ANS: B

PTS: 1

COMPLETION
1.

Converting analog data to digital signals is generally called ____________________.

ANS: digitization
PTS: 1
2.
____________________ are the electric or electromagnetic impulses used to encode and transmit data.
ANS: Signals
PTS: 1
3.
____________________ is unwanted electrical or electromagnetic energy that degrades the quality of signals and data.
ANS: Noise
PTS: 1
4.
The ____________________ of a signal is the height of the wave above (or below) a given reference point.
ANS: amplitude

PTS: 1
5.

The ____________________, or time interval, of one cycle is called its period.

ANS: length
PTS: 1
6.
The range of frequencies that a signal spans from minimum to maximum is called the
____________________.
ANS: spectrum
PTS: 1
7.
The ____________________ of a signal is the absolute value of the difference between the lowest and highest frequencies.
ANS: bandwidth
PTS: 1
8.
Because extraneous noise degrades original signals, an electronic device usually has a(n) ____________________ that is less than its bandwidth.
ANS: effective bandwidth
PTS: 1
9.
The ____________________ of a signal is the position of the waveform relative to a given moment of time, or relative to time zero.
ANS: phase
PTS: 1
10.
____________________ is a relative measure of signal loss or gain and is used to measure the logarithmic loss or gain of a signal.
ANS:
Decibel (dB)
Decibel
dB
PTS: 1
11.

____________________ is the opposite of attenuation.

ANS: Amplification
PTS: 1

12.
The ____________________ digital encoding scheme transmits 1s as zero voltages and 0s as positive voltages.
ANS:
nonreturn to zero-level (NRZ-L) nonreturn to zero-level
NRZ-L
PTS: 1
13.
With the ____________________ encoding scheme, to transmit a 1, the signal changes from low to high in the middle of the interval; to transmit a 0, the signal changes from high to low in the middle of the interval.
ANS: Manchester
PTS: 1
14.
The ____________________ encoding scheme takes 4 bits of data, converts the 4 bits into a unique 5-bit sequence, and encodes the 5 bits using NRZI.
ANS: 4B/5B
PTS: 1
15.
____________________ is a simpler form of modulation in which binary 1s and 0s are represented by uniquely different values of amplitude, frequency, or phase.
ANS: Shift keying
PTS: 1
16.
____________________ shift keying uses two different frequency ranges to represent data values of 0 and 1.
ANS: Frequency
PTS: 1
17.
____________________ is a phenomenon that occurs when the frequencies of two or more signals mix together and create new frequencies.
ANS: Intermodulation distortion
PTS: 1
18.
A(n) ____________________ converts the analog data to a digital signal by tracking the analog waveform and taking “snapshots” of the analog data at fixed intervals.
ANS: codec
PTS: 1

19.
Quantization error, or ____________________, causes the regenerated analog data to differ from the original analog data.
ANS: quantization noise
PTS: 1
20.
A problem inherent with delta modulation is that if the analog waveform rises or drops too quickly, the codec may not be able to keep up with the change, and ____________________ results. ANS: slope overload noise
PTS: 1
21.
The set of all textual characters or symbols and their corresponding binary patterns is called a(n) ____________________.
ANS: data code
PTS: 1
22.
The control character ____________________ (LF) provides control between a processor and an input/output device.
ANS: linefeed
PTS: 1
23.
The control character ____________________ (CR) provides control between a processor and an input/output device.
ANS: carriage return
PTS: 1
24.
____________________ is an encoding technique that provides a unique coding value for every character in every language, no matter what the platform.
ANS: Unicode
PTS: 1
25.
Currently, ____________________ supports more than 110 different code charts
(languages and symbol sets).
ANS: Unicode
PTS: 1
ESSAY

1.

What are the four possible data-to-signal conversion combinations?

ANS:
Data and signals are two of the basic building blocks of any computer network. It is important to understand that the terms “data” and “signal” do not mean the same thing, and that in order for a computer network to transmit data, the data must first be converted into the appropriate signals. The one thing data and signals have in common is that both can be in either analog or digital form, which gives us four possible data-to-signal conversion combinations:
* Analog data-to-analog signal, which involves amplitude and frequency modulation techniques
* Digital data-to-digital signal, which involves encoding techniques
* Digital data-to-discrete analog signal, which involves modulation techniques
* Analog data-to-digital signal, which involves digitization techniques
PTS: 1
2.

What are common examples of data?

ANS:
Common examples of data include:
* A computer file of names and addresses stored on a hard disk drive
* The bits or individual elements of a movie stored on a DVD
* The binary 1s and 0s of music stored on a compact disc or inside an iPod
* The dots (pixels) of a photograph that has been digitized by a digital camera and stored on a memory stick * The digits 0 through 9, which might represent some kind of sales figures for a business
PTS: 1
3.

What are common examples of signals?

ANS:
Common examples of signals include:
* A transmission of a telephone conversation over a telephone line
* A live television news interview from Europe transmitted over a satellite system
* A transmission of a term paper over the printer cable between a computer and a printer
* The downloading of a Web page as it transfers over the telephone line between your Internet service provider and your home computer
PTS: 1
4.

What happens when you introduce noise into digital data and digital signals?

ANS:
Noise has the properties of an analog waveform and thus can occupy an infinite range of values; digital waveforms occupy only a finite range of values. When you combine analog noise with digital waveform, it is fairly easy to separate the original digital waveform from the noise.
If the amount of noise remains low enough that the original digital waveform can still be interpreted, then the noise can be filtered out, thereby leaving the original waveform. If, however, the noise becomes so great that it is no longer possible to distinguish a high from a low, then the noise has taken over the signal and you can no longer understand this portion of the waveform.

PTS: 1
5.

What is the purpose of using digital encoding schemes?

ANS:
To transmit digital data using digital signals, the 1s and 0s of the digital data must be converted to the proper physical form that can be transmitted over a wire or airwave. Thus, if you wish to transmit a data value of 1, you could do this by transmitting a positive voltage on the medium. If you wish to transmit a data value of 0, you could transmit a zero voltage. You could also use the opposite scheme: a data value of 0 is positive voltage, and a data value of 1 is a zero voltage. Digital encoding schemes like this are used to convert the 0s and 1s of digital data into the appropriate transmission form. There are six digital encoding schemes that are representative of most digital encoding schemes: NRZ-L,
NRZI, Manchester, differential Manchester, bipolar-AMI, and 4B/5B.
PTS: 1

Chapter 3: Conducted and Wireless Media
TRUE/FALSE
1.
Category 1 twisted pair wire is not recommended for transmitting megabits of computer data.
ANS: T
2.
ANS: T
2.

3.

ANS: F
4.
installations.
ANS: F
4 wires.

5.

ANS: T pair. 6.

ANS: F

PTS: 1
Category 1 wire is susceptible to experiencing noise and signal attenuation.
PTS: 1
Category 1 twisted pair wire produces less noise and signal attenuation than Category
PTS: 1
Much of the Category 3 wire sold today is used for new computer network
PTS: 1
Category 5 twisted pair has a higher number of twists per inch than the Category 1 to
PTS: 1
Category 1 through 7 twisted pair wires can be purchased only as unshielded twisted
PTS: 1

7.
The braided metal shield is very good at blocking electromagnetic signals from entering the cable and producing noise.
ANS: T

PTS: 1

8.
A fairly common application for baseband coaxial used to be the interconnection of hubs within a local area network.
ANS: T
9.
ANS: F
10.
ANS: F

PTS: 1
Thin coaxial cable typically carries broadband signals.
PTS: 1
Thick coaxial cable has limited noise isolation and typically carries baseband signals.
PTS: 1

11.
Electromagnetic interference can be reduced with proper shielding, but it cannot be completely avoided unless you use fiber-optic cable.
ANS: T
12.
ANS: T
13.
ANS: T

PTS: 1
Fiber-optic cable cannot generate nor be disrupted by electromagnetic interference.
PTS: 1
Light traveling through air experiences little resistance.
PTS: 1

14.
It is estimated that in the future, photonic fibers will have transmission speeds and distances at least 10 times that of current fiber-optic cable.
ANS: T
15.
ANS: F
16.
ANS: T

PTS: 1
Single-mode fiber-optic cable is labeled 62.5/125 cable.
PTS: 1
Wireless transmissions generally do not have to deal with right-of-way issues.
PTS: 1

17.
Businesses can use terrestrial microwave to implement telecommunications systems between corporate buildings.
ANS: T
18.
ANS: F

PTS: 1
Microwave transmissions follow the curvature of the Earth.
PTS: 1

19.
ANS: T

One way of categorizing satellite systems is by how far the satellite is from the Earth.
PTS: 1

20.
The advantage to being closer to Earth is that the satellite must continuously circle the
Earth to remain in orbit.
ANS: F

PTS: 1

21.
Satellites that are always over the same point on Earth can be used for long periods of high-speed data transfers.
ANS: T
22.
ANS: F
23.
the Earth.
ANS: F

PTS: 1
At the end of the twentieth century, there were approximately 3000 LEO satellites.
PTS: 1
At the end of the twentieth century, approximately 105 MEO satellites were orbiting
PTS: 1

24.
Geosynchronous-Earth-orbit satellites are most commonly used for signal relays for broadcast, cable, and direct television.
ANS: T
25.
ANS: T

PTS: 1
Four basic generations of cellular telephone systems currently exist.
PTS: 1

26.
Because each cell uses low-power transmissions, it is not likely that a transmission within one particular cell will interfere with a transmission in another cell.
ANS: T
27.
technologies.
ANS: F
28.
ANS: T

PTS: 1
AMPS and D-AMPS technologies generally offer a clearer signal than all PCS
PTS: 1
General Packet Radio Service (GPRS) can transmit data at 30 kbps to 40 kbps.
PTS: 1

29.
IEEE 802.16a is a revision of the 802.16 standard that provides a high-speed connection for slowly moving devices.
ANS: F
30.

PTS: 1
Data transmission speed is the number of bits per second that can be transmitted.

ANS: T
31.

PTS: 1
ZigBee is a form of wireless technology used within buildings.

ANS: T
32.

PTS: 1
ZigBee is capable of transmitting signals for up to one mile.

ANS: F

PTS: 1

MULTIPLE CHOICE
1.
A current or signal in one wire can produce an unwanted current or signal, called
____, in a second wire.
a.

current-talk

c.

crosstalk

b.

signal-talk

d.

crossover

ANS: C

PTS: 1

2.
____ twisted pair is the least quality twisted pair wire that should be used in a data/ voice application.
a.

Category 1

c.

Category 5

b.

Category 3

d.

Category 7

ANS: A

PTS: 1

3.
____ twisted pair wire is used in environments that have a noticeable amount of electromagnetic interference.
a.

Shielded

c.

Super

b.

Congealed

d.

Dilithium

ANS: A
4.
1.544 Mbps.

PTS: 1
____ is the designation for a digital telephone circuit that transmits voice or data at

a.

ISDN

c.

VSAT

b.

T-1

d.

T-32

ANS: B

PTS: 1

5.
____ twisted pair was designed to transmit 10 Mbps of data over a local area network for distances up to 100 meters (328 feet).
a.

Category 2

c.

Category 5

b.

Category 3

d.

Category 6

ANS: B

PTS: 1

6.
Category 3 twisted pair can run farther than 100 meters from its source to its final destination, as long as the signal is regenerated at least every ____ meters.
a.
20
c.
75
b.

50

d.

ANS: D meters. 7.

100

PTS: 1
____ twisted pair was designed to transmit 20 Mbps of data for distances up to 100

a.

Category 1

c.

Category 4

b.

Category 3

d.

Category 5

ANS: C

PTS: 1

8.
____ twisted pair is designed to support data transmission with signals as high as 200
MHz for 100 meters.
a.

Category 6

c.

Category 7a

b.

Category 7

d.

Category 7e

ANS: A
9.

PTS: 1
In a(n) ____ none of the wires is wrapped with a metal foil or braid.

a.

shielded twisted pair
(STP)

c.

CAT 4 twisted pair

b.

unshielded twisted pair
(UTP)

d.

CAT 7 twisted pair

ANS: B

PTS: 1

10.
____ is a form in which a shield is wrapped around each wire individually, around all the wires together, or both.
a.

Shielded twisted pair
(STP)

c.

CAT 2 twisted pair

b.

Unshielded twisted pair
(UTP)

d.

CAT 5 twisted pair

ANS: A

PTS: 1

11.
Because of its good shielding properties, ____ is good at carrying analog signals with a wide range of frequencies.
a.

CAT 1 wire

c.

copper wire

b.

CAT 2 wire

d.

coaxial cable

ANS: D
12.
digital data.

PTS: 1
____ technology uses digital signaling in which the cable carries only one channel of

a.

Broadband coaxial

c.

Baseband coaxial

b.

CAT 7

d.

Fiber optic

ANS: C

PTS: 1

13.
____ technology typically transmits analog signals and is capable of supporting multiple channels of data simultaneously.
a.

Broadband coaxial

c.

Baseband coaxial

b.

CAT 7

d.

Fiber optic

ANS: A
14.
diameter.

PTS: 1
____ cable ranges in size from approximately 6 to 10 mm or more (1/4 to 3/8 inch) in

a.

Thin coaxial

c.

CAT 2

b.

Thick coaxial

d.

CAT 3

ANS: B
15.

PTS: 1
____ cable is approximately 4 mm (less than 1/4 inch) in diameter.

a.

CAT 2

c.

Thin coaxial

b.

Thick coaxial

d.

CAT 3

ANS: C cable. 16.

PTS: 1
____ cable contains, as the name implies, a single copper wire in the center of the

a.

Braided coaxial

c.

thin-stranded coaxial

b.

Fiber optic

d.

Single-stranded coaxial

ANS: D

PTS: 1

17.
____ cable is a thin glass cable, a little thicker than a human hair, surrounded by a plastic coating.
a.

Single-stranded coaxial

c.

Braided coaxial

b.

Fiber-optic

d.

CAT 7

ANS: B
18.

PTS: 1
____ cable is virtually impossible to wiretap.

a.

CAT 1

c.

Thick coaxial

b.

Single-stranded coaxial

d.

Fiber-optic

ANS: D
____.

19.

PTS: 1
As the length of a glass cable grows, the light signal attenuates due to reflection and

a.

EMI

c.

refraction

b.

RFI

d.

friction

ANS: C

PTS: 1

20.
The ____ cable is similar to fiber-optic cable in that it is as thin as a hair and transparent. The big difference, however, is that this new cable is full of holes.
a.

photonic fiber

c.

thick coaxial

b.

single-stranded coaxial

d.

thin coaxial

ANS: A

PTS: 1

21.
When a light signal inside the cable bounces off the cable wall and back into the cable, this is called ____.
a.

refraction

c.

blinking

b.

reflection

d.

friction

ANS: B

PTS: 1

22.
____ transmission requires the use of a very thin fiber-optic cable and a very focused light source, such as a laser.
a.

Multimode

c.

Single-mode

b.

Reflection

d.

Refraction

ANS: C

PTS: 1

23.
____ transmission uses a slightly thicker fiber cable and an unfocused light source, such as an LED.
a.

Multimode

c.

Single-mode

b.

Reflection

d.

Refraction

ANS: A

PTS: 1

24.
____ transmission systems transmit tightly focused beams of radio signals from one ground-based microwave transmission antenna to another.
a.

Satellite

c.

Downlink

b.

Cellular

d.

Terrestrial microwave

ANS: D

PTS: 1

25.
____ transmission means that to receive and transmit a signal, each antenna must be in sight of the next antenna.
a.

Uplink

c.

Line-of-sight

b.

Omnidirectional

d.

Downlink

ANS: C

PTS: 1

26. miles. a.
3
b.

The typical maximum distance between microwave towers is roughly ____ to 30
c.
d.

6

ANS: D

8
15

PTS: 1

27.
____ transmission systems are similar to terrestrial microwave systems except that the signal travels from a ground station on Earth to a satellite and back to another ground station on Earth.
a.

Satellite microwave

c.

Downlink

b.

Cellular

d.

Terrestrial microwave

ANS: A

PTS: 1

28.
The closer a satellite is to the Earth, the shorter the times required to send data to the satellite, that is, to ____.
a.

downlink

c.

download

b.

uplink

d.

send down

ANS: B

PTS: 1

29.
The transmission time from when a signal first leaves a satellite and then arrives at a ground station is called ____.
a.

propagation delay

c.

uplink

b.

downlink

d.

upload

ANS: A
30.

PTS: 1
____ satellites are closest to the Earth.

a.

Low-Earth-orbit (LEO)

c.

Geosynchronous-Earth-orbit (GEO)

b.

Middle-Earth-orbit
(MEO)

d.

Highly-elliptical-Earth-orbit (HEO)

ANS: A
31.

PTS: 1
____ satellites can be found roughly 1000 to 3000 miles from the Earth.

a.

Low-Earth-orbit (LEO)

c.

Geosynchronous-Earth-orbit (GEO)

b.

Middle-Earth-orbit
(MEO)

d.

Highly-elliptical-Earth-orbit (HEO)

ANS: B

PTS: 1

32.
A recently publicized satellite system that has unique properties is the ____ satellite, which is used by governments for spying and by scientific agencies for observing celestial bodies.
a.

Low-Earth-orbit (LEO)

c.

Geosynchronous-Earth-orbit (GEO)

b.

Middle-Earth-orbit
(MEO)

d.

Highly-elliptical-Earth-orbit (HEO)

ANS: D

PTS: 1

33.
Cells, in a cellular telephone system, can range in size from one-half mile in radius to
____ miles in radius.
a.
25
c.
50
b.

35

ANS: C
34.

d.

70

PTS: 1
____ is the first-generation cellular telephone system.

a.

Personal Communications Services (PCS)

b.

Time Division Multiple Access (TDMA)

c.

Advanced Mobile Phone Service (AMPS)

d.

Global System for Mobile (GSM) Communications

ANS: C

PTS: 1

35.
The ____ system is an example of a single-user Earth station satellite system with its own ground station and a small antenna (two to six feet across).
a.

T1

c.

VSAT

b.

LEO

d.

SAT-V

ANS: C
36.

PTS: 1
The first PCS technology uses a form of time division multiplexing called ____.

a.

Code Division Multiple Access (CDMA)

b.

Time Division Multiple Access (TDMA)

c.

Global System for Mobile (GSM) Communications

d.

Digital-Advanced Mobile Phone Service (D-AMPS)

ANS: B

PTS: 1

37.
The third PCS technology is ____ and uses a different form of time division multiple access technology.
a.

Global System for Mobile (GSM) Communications

b.

Time Division Multiple Access (TDMA)

c.

Code Division Multiple Access (CDMA)

d.

Digital-Advanced Mobile Phone Service (D-AMPS)

ANS: A

PTS: 1

38.
____ is a broadband wireless transmission technology that is based upon a series of
IEEE standards.
a.

WiFi

c.

IrDA

b.

Bluetooth

ANS: D

d.

WiMAX

PTS: 1

39.
____ systems transmit data over a wide range of frequencies rather than limiting transmissions to a narrow, fixed band of frequencies.
a.

WiFi

c.

Ultra-wideband

b.

Bluetooth

d.

Free space optics

ANS: C
40.

PTS: 1
____ systems are good at sending low-speed signals over short to medium distances.

a.

Microwave

c.

WiFi

b.

Satellite

d.

ZigBee

ANS: D

PTS: 1

41.
The popular GPS devices that people use to find directions while driving use which type of satellite system?
a.

LEO

c.

GEO

b.

MEO

d.

HEO

ANS: B
42.

PTS: 1
Which type of satellite remains located over the same point of earth at all times?

a.

LEO

c.

GEO

b.

MEO

d.

HEO

ANS: C

PTS: 1

COMPLETION
1.
____________________ wire comes as two or more pairs of single-conductor copper wires that have been twisted around each other.
ANS: Twisted pair
PTS: 1
2.
____________________ twisted pair is designed to carry analog voice or digital data at low speeds (less than or equal to 9600 bps) and is now obsolete.
ANS:
Category 1
CAT 1
PTS: 1

3.
A(n) ____________________ is a device that generates a new signal by creating an exact replica of the original signal.
ANS: repeater
PTS: 1
4.
____________________ twisted pair was designed to transmit 100 Mbps of data for distances up to 100 meters.
ANS:
Category 5
CAT 5
PTS: 1

meters.

5.

____________________ wire is designed to support 600 MHz of bandwidth for 100

ANS:
Category 7
CAT 7
PTS: 1
6.

____________________ is the most common form of twisted pair.

ANS:
Unshielded twisted pair (UTP)
Unshielded twisted pair
UTP
PTS: 1
7.
____________________ cable, in its simplest form, is a single wire (usually copper) wrapped in a foam insulation, surrounded by a braided metal shield, then covered in a plastic jacket.
ANS: Coaxial
PTS: 1
8.
Two major coaxial cable technologies exist and are distinguished by the type of signal each carries: baseband and ____________________.
ANS: broadband
PTS: 1
9.
Coaxial cable is available in a variety of thicknesses, with two primary physical types: thick coaxial cable and ____________________ coaxial cable.
ANS: thin

PTS: 1
10.
____________________ cable is composed of many fine wires twisted around each other, acting as a single conductor.
ANS: Braided coaxial
PTS: 1
11.
____________________ is the electronic distortion that a signal passing through a metal wire experiences when a stray magnetic field passes over it.
ANS: Electromagnetic interference
PTS: 1
12.
The ____________________ is the main connecting cable that runs from one end of the installation to another.
ANS: backbone
PTS: 1
13.
When a light signal passes from the core of the cable into the surrounding material, this is called ____________________.
ANS: refraction
PTS: 1
14.

Multimode fiber-optic cable is labeled ____________________ cable.

ANS: 62.5/125
PTS: 1
15.
____________________ is the legal capability of a business to install a wire or cable across someone’s property.
ANS: Right-of-way
PTS: 1
16.
The two most common application areas of terrestrial microwave are
____________________ and business intercommunication.
ANS: telephone communications
PTS: 1
17.
The closer a satellite is to the Earth, the shorter the times required to receive data from the satellite, that is, to ____________________.

ANS: downlink
PTS: 1
18.
____________________ satellites can be found as close as 100 miles from the surface and as far as 1000 miles.
ANS:
Low-Earth-orbit (LEO)
Low-Earth-orbit
LEO
PTS: 1
19.
The ____________________ is a system of 24 satellites that were launched by the
U.S. Department of Defense and are used for identifying locations on Earth.
ANS:
global positioning system (GPS) global positioning system
GPS
PTS: 1
20.
____________________ satellites are found 22,300 miles from the Earth and are always positioned over the same point on Earth.
ANS:
Geosynchronous-Earth-orbit (GEO)
Geosynchronous-Earth-orbit
GEO
PTS: 1
21.

____________________ is the digital equivalent of analog cellular telephone service.

ANS:
Digital-Advanced Mobile Phone Service (D-AMPS)
Digital-Advanced Mobile Phone Service
D-AMPS
PTS: 1
22.
The second-generation PCS cell phone technology used both GSM and
____________________ technology.
ANS:
Code Division Multiple Access (CDMA)
Code Division Multiple Access
CDMA
PTS: 1

23.
____________________ transmission is a special form of radio transmission that uses a focused ray of light in the infrared frequency range (1012 –1014 MHz).
ANS: Infrared
PTS: 1
24.
A(n) ____________________ system is one of the latest techniques for delivering
Internet services into homes and businesses.
ANS: broadband wireless
PTS: 1
25.
____________________ uses lasers, or, in some cases, infrared transmitting devices, to transmit data between two buildings over short distances, like across the street.
ANS: Free space optics
PTS: 1
ESSAY
1.

Briefly explain the characteristics of Category 5e twisted pair.

ANS:
Approved at the end of 1999, the specification for Category 5e twisted pair is similar to Category 5’s in that this wire is also recommended for transmissions of 100 Mbps (100 MHz) for 100 meters. Many companies are producing Category 5e wire at 125 MHz for 100 meters. While the specifications for the earlier Category 1 to 5 wires described only the individual wires, the Category 5e specification indicates exactly four pairs of wires and provides designations for the connectors on the ends of the wires, patch cords, and other possible components that connect directly with a cable. Thus, as a more detailed specification than Category 5, Category 5e can better support the higher speeds of 100-Mbps
(and higher) local area networks.
PTS: 1 wire. 2.

Explain when shielded twisted pair wire works better than unshielded twisted pair

ANS:
If a twisted pair wire needs to go through walls, rooms, or buildings where there is sufficient electromagnetic interference to cause substantial noise problems, using shielded twisted pair can provide a higher level of isolation from that interference than unshielded twisted pair wire, and thus a lower level of errors. Electromagnetic interference is often generated by large motors, such as those found in heating and cooling equipment or manufacturing equipment. Even fluorescent light fixtures generate a noticeable amount of electromagnetic interference. Large sources of power can also generate damaging amounts of electromagnetic interference. Therefore, it is generally not a good idea to strap twisted pair wiring to a power line that runs through a room or through walls. Furthermore, even though Categories 3 to 6 shielded twisted pair have improved noise isolation, you cannot expect to push them past the 100-meter limit. Finally, be prepared to pay a premium for shielded twisted pair.

It is not uncommon to spend an additional $1 per foot for good-quality shielded twisted pair. In contrast, Category 5, 5e, and 6 UTP often cost between $.10 and $.20 per foot.
PTS: 1
3.

How does a fiber-optic cable transmit data?

ANS:
A light source, called a photo diode, is placed at the transmitting end and quickly switched on and off to produce light pulses. These light pulses travel down the glass cable and are detected by an optic sensor called a photo receptor on the receiving end. The light source can be either a simple and inexpensive light-emitting diode (LED), such as those found in many pocket calculators, or a more complex laser. The laser is much more expensive than the LED, and it can produce much higher data transmission rates. Fiber-optic cable is capable of transmitting data at over 100 Gbps (that’s 100 billion bits per second!) over several kilometers. Because many common local area network installations use an LED source, however, real-world fiber-optic transmissions are effectively limited to 10 gigabits for
300 meters.
PTS: 1
4.

What are the disadvantages of fiber-optic cables?

ANS:
Fiber-optic cable has two small but significant disadvantages. First, due to the way the light source and photo receptor arrangement works, light pulses can travel in one direction only. Thus, to support a twoway transmission of data, two fiber-optic cables are necessary. For this reason, most fiber-optic cable is sold with at least two (if not more) individual strands of fiber bundled into a single package.
A second disadvantage of fiber-optic cable is its higher cost, but this disadvantage is slowly disappearing. For example, it is now possible to purchase bulk, general purpose duplex (two-strand) fiber-optic cable for approximately $.50 per foot (as opposed to paying a few dollars per foot several years ago), which is close to the price of many types of coaxial cable and shielded twisted pair cable.
PTS: 1
5.

What are the main characteristics of the multiplexed Earth station satellite topology?

ANS:
In a multiplexed Earth station satellite system, the ground station accepts input from multiple sources and in some fashion interweaves the data streams, either by assigning different frequencies to different signals or by allowing different signals to take turns transmitting. How does this type of satellite system satisfy the requests of users and assign time slots? Each user could be asked in turn if he or she has data to transmit, but because so much time could be lost by the asking process, this technique would not be economically feasible. A first-come, first-served scenario, in which each user competed with every other user, would also be an extremely inefficient design. The technique that seems to work best for assigning access to multiplexed satellite systems is a reservation system. In a reservation system, users place a reservation for future time slots. When the reserved time slot arrives, the user transmits his or her data on the system. Two types of reservation systems exist: centralized reservation and distributed reservation. In a centralized reservation system, all reservations go to a central location, and that site handles the incoming requests. In a distributed reservation system, no central site handles the reservations, but individual users come to some agreement on the order of transmission.

PTS: 1

Chapter 4: Making Connections
TRUE/FALSE
1.
On occasion, a company will create a protocol that, while not an official standard, becomes so popular that other companies start using it.
ANS: T
2.
ANS: F
3.
ANS: T

PTS: 1
One of the latest interface standards is the RS-232 interface.
PTS: 1
An EIA-232F interface is a full-duplex connection.
PTS: 1

4.
Because USB provides a digital interface, it is necessary to convert the digital signals of the microcomputer to analog signals for transfer over a connection.
ANS: F

PTS: 1

5.
When using peripherals that are designed with a USB connector, it is also possible to connect one USB peripheral to another.
ANS: T
6.
ANS: F
7.
components.
ANS: T
8.
ANS: T

PTS: 1
USB is an example of a full-duplex connection.
PTS: 1
The procedural component of USB is probably the most involved of the four
PTS: 1
FireWire is similar to USB in that it is hot pluggable.
PTS: 1

9.
To take advantage of the higher-speed interface of SCSI, you need to install a SCSI adapter in your computer.
ANS: T
10.
switches.
ANS: T

PTS: 1
Rather than being a single shared bus, InfiniBand is a network of high-speed links and
PTS: 1

11.
ANS: F
12.
ANS: F
13.
ANS: F
14.
ANS: T

An asynchronous connection is the most complex example of a data link protocol.
PTS: 1
A start bit is always a 1.
PTS: 1
A stop bit is always a 0.
PTS: 1
The starting and ending sequences of the synchronous connection are called flags.
PTS: 1

15.
Because of their higher efficiency, asynchronous connections have almost completely replaced synchronous connections.
ANS: F
16.
ANS: T
17.
ANS: F

PTS: 1
Examples of real-time applications usually include streaming voice, video, and music.
PTS: 1
Neither USB nor FireWire support isochronous connections.
PTS: 1

18.
If control simplicity is your primary goal, point-to-point connection of terminals is clearly superior to multipoint connections.
ANS: T

PTS: 1

MULTIPLE CHOICE
1.

The connection to a peripheral is often called the ____.

a.

USB

c.

FireWire

b.

interface

d.

EIA-232F

ANS: B

PTS: 1

2.
An interface standard can consist of four parts, or components, all of which reside at the ____ layer.
a.

network

c.

physical

b.

data link

d.

transport

ANS: C

PTS: 1

3.
An interface standard can consist of four parts, or components: the electrical component, the mechanical component, the ____ component, and the procedural component.
a.
functional
c.
administrative
b.

automatic

ANS: A
4.
description.

d.

organizational

PTS: 1
The ____ component of an interface deals with items such as the connector or plug

a.

administrative

c.

procedural

b.

functional

d.

mechanical

ANS: D

PTS: 1

5.
The ____ component of an interface describes how the particular circuits are used to perform an operation.
a.

electrical

c.

procedural

b.

functional

d.

mechanical

ANS: C

PTS: 1

6.
In modem interfacing terminology, the computer (or terminal) end of an interface is referred to as ____.
a.

data communicating equipment (DCE)

c.

data transmitting equipment (DTE)

b.

data terminating equipment (DTE)

d.

data receiving equipment (DRE)

ANS: B
7.

PTS: 1
In modem interfacing terminology, the modem is referred to as the ____.

a.

data communicating equipment (DCE)

c.

data transmitting equipment (DTE)

b.

data terminating equipment (DTE)

d.

data receiving equipment (DRE)

ANS: A

PTS: 1

8.
To define functional and procedural components, EIA-232F incorporates the ITU’s
____ standard.
a.

ISO 2110

c.

RS-232

b.

V.28

d.

V.24

ANS: D time. 9.

PTS: 1
A ____ connection is one in which both sender and receiver may transmit at the same

a.

full-duplex

c.

single-duplex

b.

half-duplex

d.

multi-duplex

ANS: A

PTS: 1

10.
Some systems, for various reasons, allow only one side or the other to transmit at one time. This type of connection is an example of a ____ connection.
a.

full-duplex

c.

single-duplex

b.

half-duplex

d.

multi-duplex

ANS: B

PTS: 1

11.
The idea behind ____ is that the peripheral can simply be plugged in and turned on, and that the computer should dynamically recognize the device and establish the interface.
a.

RS-232

c.

daisy-chaining

b.

EIA-232F

d.

hot plugging

ANS: D

PTS: 1

12.
The ____ component of USB strictly specifies the exact dimensions of the interface’s connectors and cabling.
a.

procedural

c.

mechanical

b.

functional

d.

electrical

ANS: C
13.

PTS: 1
A(n) ____ is simply a high-speed connection to which multiple devices can attach.

a.

pin

c.

circuit

b.

bus

d.

interface

ANS: B

PTS: 1

14.
FireWire supports two types of data connections: an asynchronous connection and a(n) ____ connection.
a.

synchronous

c.

parallel

b.

timed

d.

isochronous

ANS: D

PTS: 1

15.
____ is a technique for interfacing a computer to high-speed devices such as hard disk drives, tape drives, CDs, and DVDs.
a.

Serial

c.

SCSI

b.

RS-232

d.

EIA-232F

ANS: C
16.

PTS: 1
SCSI is a ____ interface and not just an interface technique for hard disk drives.

a.

systems

c.

server

b.

terminal

d.

driver

ANS: A
17.

PTS: 1
You can connect up to ____ different SCSI devices to one SCSI adapter.

a.

2

c.

6

b.

4

d.

7

ANS: D
18.

time.

PTS: 1
____ is a serial connection or bus that can carry multiple channels of data at the same

a.

InfiniBand

c.

SCSI

b.

Fibre Channel

d.

USB

ANS: A

second.

19.

PTS: 1
InfiniBand can support data transfer speeds of all of the following EXCEPT ____ per

a.

1.5 billion bits (1.5 gigabits) c.

5 billion bits (5 gigabits)

b.

2.5 billion bits (2.5 gigabits) d.

10 billion bits (10 gigabits)

ANS: A

PTS: 1

20.
InfiniBand can address (interconnect) ____ of devices, using both copper wire and fiber-optic cables.
a.

tens

c.

thousands

b.

hundreds

d.

millions

ANS: C
21.

PTS: 1
Fibre Channel can support the interconnection of up to ____ devices only.

a.

56

c.

256

b.

126

d.

512

ANS: B

PTS: 1

22.
To prepare a data character for transmission, a ____ bit is added to the beginning of the character and informs the receiver that an incoming data frame is arriving.
a.

start

c.

end

b.

stop

d.

parity

ANS: A

PTS: 1

23. frame. a. start b.

At the end of the data character, one or two ____ bits are added to signal the end of the
c.
d.

parity

ANS: D

check stop PTS: 1

24.

With a(n) ____ connection, the unit of transmission is a sequence of characters.

a.

asynchronous

c.

synchronous

b.

parity

d.

serial

ANS: C
25.
connection.

PTS: 1
A direct connection between a terminal and a mainframe computer is a ____

a.

multipoint

c.

single-point

b.

point-to-point

d.

direct-point

ANS: B
26.

PTS: 1
During the early years of computing, a mainframe computer was called the ____.

a.

secondary

c.

dumb end

b.

terminal

d.

primary

ANS: D
27.

PTS: 1
During the early years of computing, a terminal was called the ____.

a.

secondary

c.

dumb end

b.

terminal

d.

primary

ANS: A

PTS: 1

28.
A primary that performs ____ polling polls only the first terminal, which then passes the poll to the second terminal, and each successive terminal passes the poll along.
a.

roll-call

c.

hub

b.

selection

d.

terminal

ANS: C line. 29.

PTS: 1
With ____ connections, polling is not necessary because there is only one terminal per

a.

point-to-point

c.

terminal-to-point

b.

multipoint

d.

primary-to-point

ANS: A
COMPLETION

PTS: 1

1.
The process of providing all the proper interconnections between a computer and a peripheral is called ____________________.
ANS: interfacing
PTS: 1
2.
The ____________________ component of an interface deals with voltages, line capacitance, and other electrical issues.
ANS: electrical
PTS: 1
3.
The ____________________ component of an interface describes the function of each pin that is used in a particular interface.
ANS: functional
PTS: 1
4.
____________________ is an interface standard for connecting a computer or terminal (or DTE) to a voice-grade modem (or DCE) for use on analog public telecommunications systems. ANS: EIA-232F
PTS: 1
5.
____________________ is a digital interface that uses a standardized connector
(plug) for all serial and parallel type devices.
ANS:
Universal Serial Bus (USB)
Universal Serial Bus
USB
PTS: 1
6.
The technique of connecting a device to each subsequent device (instead of back to the computer) is known as ____________________.
ANS: daisy-chaining
PTS: 1
7.
____________________ is a process in which a computer asks a peripheral if it has any data to transmit to the computer.
ANS: Polling
PTS: 1

8.
____________________ is an easy-to-use, flexible, and low-cost digital interface that is capable of supporting transfer speeds of up to 3.2 Gbps.
ANS: FireWire
PTS: 1
9.
____________________ connection provides guaranteed data transport at a predetermined rate.
ANS: Isochronous
PTS: 1
10.
the Internet.

____________________ is a technique for interfacing disk storage to a computer via

ANS:
Internet SCSI (iSCSI) iSCSI PTS: 1
11.
____________________ is similar to InfiniBand in that it too is a serial, high-speed network that connects a computer to multiple input/output devices.
ANS: Fibre Channel
PTS: 1
12.
In a(n) ____________________ connection, a single character, or byte of data, is the unit of transfer between the sender and receiver.
ANS: asynchronous
PTS: 1
13.
To prepare a data character for an asynchronous transmission, a few extra bits of information are added to the data bits of the character to create a(n) ____________________.
ANS: frame
PTS: 1
14.
ANS: parity
PTS: 1

A(n) ____________________ bit performs an error check on only the data bits.

15.
A(n) ____________________ connection is a special kind of data link connection used to support various types of real-time applications.
ANS: isochronous
PTS: 1
16.
A(n) ____________________ connection is a single wire with the mainframe connected on one end and multiple terminals connected on the other end.
ANS: multipoint
PTS: 1
17.
A technique called ____________________, which allows only one terminal to transmit at one time, successfully controls multiple terminals that share a connection to a mainframe computer. ANS: polling
PTS: 1
18.
____________________ polling is the polling method in which the mainframe computer (primary) polls each terminal (secondary), one at a time, in round-robin fashion.
ANS: Roll-call
PTS: 1
19.
In ____________________, the primary creates a packet of data with the address of the intended terminal and transmits the packet.
ANS: selection
PTS: 1

ESSAY
1.

What are the primary organizations involved in making interface standards?

ANS:
The primary organizations involved in making standards are:
* International Telecommunication Union (ITU), formerly the Consultative Committee on
International Telegraphy and Telephony (CCITT)
* Electronic Industries Association (EIA)
* Institute for Electrical and Electronics Engineers (IEEE)
* International Organization for Standardization (ISO)
* American National Standards Institute (ANSI)
PTS: 1
2.

What are the standards that conform the EIA-232F interface standard?

ANS:
The EIA-232F interface standard is actually a composite of several other standards: the ITU V.28 standard, which defines EIA-232F’s electrical component; the ISO 2110 standard, which defines the mechanical component; and the ITU V.24 standard, which defines the functional and procedural components. PTS: 1
3.

What was the early disadvantage of USB?

ANS:
An early disadvantage of USB, at least when compared to other high-speed interfaces (such as
FireWire), was its relatively slow speed. USB version 1.1 has a maximum transfer speed of 12 Mbps, significantly slower than FireWire’s 400 Mbps. Fortunately, USB version 2.0 has a maximum transfer speed of 480 Mbps and is backwards compatible with the earlier 1.1 version, allowing devices with the newer interface to connect with the older interface (but at the 12-Mbps speed). More precisely, USB
2.0 can support low-speed (10 to 100 kbps) devices such as keyboards, mice, and game peripherals; full-speed (500 kbps to 10 Mbps) devices such as telephone circuits, audio, and compressed video; and high-speed devices (speeds greater than 10 Mbps) such as video, imaging devices, and broadband.
PTS: 1
4.

What are the advantages and disadvantages of an asynchronous connection?

ANS:
An asynchronous connection has advantages and disadvantages. On the positive side, generation of the start, stop, and parity bits is simple and requires little hardware or software. On the negative side, an asynchronous connection has one disadvantage in particular that cannot be overlooked. Given that seven data bits (ASCII character code set) are often combined with one start bit, one stop bit, and one parity bit, the resulting transmitted character contains three check bits and seven data bits, for a 3:7 ratio. In this scenario of 10 total check and data bits, 3 out of 10—or 30 percent—of the bits are used as check bits. This ratio of check bits to data bits is not very efficient for high amounts of data transfer and, therefore, results in slow data transfers.
PTS: 1
5.
connections?

What are the three ways used to maintain synchronization in synchronous

ANS:
Three ways are used to maintain synchronization in synchronous connections:
1. Send a synchronizing clock signal over a separate line that runs parallel to the data stream. As the data arrives on one line, a clock signal arrives on a second line. The receiver can use this clock signal to stay synchronized with the incoming data.
2. If transmitting a digital signal, use a Manchester code. Because a Manchester code always has a signal transition in the middle of each bit, the receiver can anticipate this signal transition and read the incoming data stream with no errors. A Manchester-encoded digital signal is an example of a selfclocking signal.
3. If transmitting an analog signal, use the properties of the analog signal itself for self-clocking. For example, an analog signal with a periodic phase change can provide the necessary synchronization.
PTS: 1

Chapter 5: Making Connections Efficient: Multiplexing and Compression
TRUE/FALSE
1.
One way to make a connection between two devices more efficient is to compress the data that transfers over the connection.
ANS: T
2.
ANS: F
3.
ANS: F
4.
ANS: T
5.
ANS: T

PTS: 1
Frequency division multiplexing is the latest multiplexing technique.
PTS: 1
In frequency division multiplexing, the signal is digital.
PTS: 1
Cell phones are an example of dynamically assigned channels.
PTS: 1
Time division multiplexing (TDM) allows only one user at a time to transmit.
PTS: 1

6.
As with a simple connection between one sending device and one receiving device, maintaining synchronization across a multiplexed link is important.
ANS: T

PTS: 1

7.
The T-1’s original purpose was to provide a high-speed connection between AT&T’s switching centers.
ANS: T
8.
ANS: F
9.
ANS: T
10.
ANS: T
11.
ANS: F
12.

PTS: 1
The T-1 system is a classic application of frequency division multiplexing.
PTS: 1
A T-1 system sends the equivalent of 24 voice grade telephone lines over one line.
PTS: 1
A T-1 system continuously sends a signal, even if there is no real data to transmit.
PTS: 1
SONET is a more modern term for the older T-1 system.
PTS: 1
SDH was developed in Europe by ITU-T.

ANS: T
13.
connection.
ANS: T
14.
ANS: F
15.
based media.
ANS: T

PTS: 1
SONET and SDH are able to multiplex varying speed streams of data onto one fiber
PTS: 1
The data rate of OC-3 is exactly thirty times the rate of OC-1.
PTS: 1
The STS multiplexor in a SONET network can accept electrical signals from copperPTS: 1

16.
Both frequency division multiplexing and synchronous time division multiplexing can waste unused transmission space.
ANS: T
17.
technique.
ANS: F
18.
ANS: T

PTS: 1
Wavelength division multiplexing (WDM) is, in essence, a time division multiplexing
PTS: 1
WDM supports multiple lambdas.
PTS: 1

19.
Dense wavelength division multiplexing is an expensive way to transmit signals from multiple devices due to the high number of differently colored lasers required in one unit.
ANS: T
20.
ANS: T

PTS: 1
DSL is capable of achieving speeds into the millions of bits per second.
PTS: 1

21.
Code division multiplexing is based upon a class of modulation techniques known as spread spectrum technology.
ANS: T

PTS: 1

22.
The big advantage of frequency division multiplexing over synchronous TDM is the lower noise due to the use of digital signals during transmission.
ANS: F

PTS: 1

23.
Synchronous time division multiplexing does not require as high-speed a line as statistical time division multiplexing does.

ANS: F

PTS: 1

24.
Code division multiplexing, while using a fairly wide bandwidth of frequencies and a complex technology, is scalable like WDM.
ANS: T

PTS: 1

25.
The basic way to perform compression is to look for some common pattern in the data and replace each data pattern with a symbol or symbols that will consume less space during transmission or storage.
ANS: T
26.

PTS: 1
The Lempel-Ziv algorithm can be fairly effective in compressing data.

ANS: T

PTS: 1

27.
The human ear can hear sounds only within a certain range, which for an average person is 10 Hz to 40 kHz (40,000 Hz).
ANS: F

PTS: 1

28.
The MP3 encoder produces a data stream that has a much faster data rate than that of conventional CD-quality music.
ANS: F
29.

PTS: 1
A video device displays multiple (typically 30) frames per second.

ANS: T

PTS: 1

MULTIPLE CHOICE
1.
Presently, a medium can be divided in three basic ways: a division of ____, a division of time, and a division of transmission codes.
a.

frequencies

c.

wavelength

b.

amplitudes

d.

direction

ANS: A
2.
medium.

PTS: 1
____ is the assignment of nonoverlapping frequency ranges to each “user” of a

a.

Time division multiplexing (TDM)

c.

Amplitude division multiplexing (ADM)

b.

Transmission code multiplexing (TCM)

d.

Frequency division multiplexing (FDM)

ANS: D
____.

3.

PTS: 1
To allow multiple users to share a single medium, FDM assigns each user a separate

a.

time slot

c.

channel

b.

transmission code

d.

amplitude

ANS: C

PTS: 1

4.
First-generation cellular telephone systems allocated channels using frequency ranges within the 800 to ____ megahertz (MHz) spectrum.
a.

830

c.

930

b.

900

d.

960

ANS: B

PTS: 1

5.
The device that is attached to the receiving end of the medium and splits off each signal to deliver it to the appropriate receiver is called the second multiplexor, or ____.
a.

multiplexor

c.

splitxor

b.

endplexor

d.

demultiplexor

ANS: D

PTS: 1

6.
In FDM, ____ take up frequencies that might be used for other data channels, thus introducing a certain level of wastefulness.
a.

guard bands

c.

multiplexors

b.

channels

d.

demultiplexors

ANS: A

PTS: 1

7.
Since time division multiplexing was introduced, it has split into two roughly parallel but separate technologies: synchronous time division multiplexing and ____ time division multiplexing. a.

fixed

c.

inverse

b.

statistical

d.

empirical

ANS: B

PTS: 1

8.
____ gives each incoming source signal a turn to be transmitted, proceeding through the sources in round-robin fashion.
a.

Statistical time division multiplexing (Stat TDM)

b.

Empirical time division multiplexing (ETDM)

c.

Synchronous time division multiplexing (Sync TDM)

d.

Fixed time division multiplexing (FTDM)

ANS: C

PTS: 1

9.
Under normal circumstances, the synchronous time division multiplexor maintains a simple ____ sampling order of the input devices.
a.

round-robin

c.

LIFO

b.

FIFO

d.

ANS: A

FILO

PTS: 1

10.
Three types of synchronous time division multiplexing that are popular today are T-1 multiplexing, ____ multiplexing, and SDH.
a.

EIA-232F

c.

SONET

b.

IPS/SPX

d.

RS-232

ANS: C

PTS: 1

11.
In the 1960s, AT&T created a service known as ____, which multiplexed digital data and digitized voice onto a high-speed telephone line with a data rate of 1.544 megabits per second.
a.

ISDN

c.

SONET

b.

T-1

d.

SDH

ANS: B
12.

PTS: 1
____ multiplexing is the multiplexing technique used to support SONET.

a.

FDM

c.

Frequency division

b.

ADM

d.

Synchronous time division

ANS: D
13.

PTS: 1
A ____ multiplexes 24 input channels together onto one high-speed telephone line.

a.

T-1 system

c.

SDH system

b.

SONET system

d.

congruent system

ANS: A
14.

PTS: 1
A T-1 system multiplexes _______ into each frame.

a.

a single ASCII character

c.

a single SYNC bit

b.

a single LENGTH byte

d.

a single SYNC byte

ANS: C
15.

PTS: 1
SONET was developed in the United States by ____.

a.

ISO

c.

IEEE

b.

ANSI

d.

IETF

ANS: B
16.

PTS: 1
SONET and SDH are both ____ multiplexing techniques.

a.

synchronous

c.

empirical

b.

statistical

d.

random

ANS: A

a.
b.

PTS: 1

17.
SONET defines a hierarchy of signaling levels, or data transmission rates, called ____. statistical transport
c.
asynchronous transport signals (ATS) signals (StatTS) empirical transport signals (ETS)

ANS: D
18.

d.

synchronous transport signals (STS)

PTS: 1
It is relatively simple to multiplex four STS-12 signals into one ____ signal.

a.

STS-8

c.

STS-32

b.

STS-16

d.

STS-48

ANS: D
19.

PTS: 1
The STS-1 signaling level supports ____ frames per second.

a.

8000

c.

32000

b.

16000

d.

64000

ANS: A
20.
multiplexing.

PTS: 1
Statistical time division multiplexing is sometimes called ____ time division

a.

empirical

c.

asynchronous

b.

random

d.

synchronous

ANS: C
21.

PTS: 1
____ multiplexes multiple data streams onto a single fiber-optic line.

a.

Statistical time division multiplexing (Stat TDM)

b.

Wavelength division multiplexing (WDM)

c.

Time division multiplexing (TDM)

d.

Channel division multiplexing (CDM)

ANS: B

PTS: 1

22.
____ uses different wavelength (frequency) lasers to transmit multiple signals at the same time over a single medium.
a.

Wave division multiplexing c.

Channel division multiplexing

b.

Statistical time division multiplexing d.

Time division multiplexing

ANS: A

PTS: 1

23.
____ is designed for short-distance connections and has only a few lambdas, with a greater space between lambdas.

a.

Dense wavelength division multiplexing (DWDM)

b.

Fixed wavelength division multiplexing (FWDM)

c.

Coarse wavelength division multiplexing (CWDM)

d.

Inverse wavelength division multiplexing (IWDM)

ANS: C
24.

PTS: 1
____ is the technology behind the popular digital subscriber line (DSL) system.

a.

Time division

c.

Wavelength division

b.

Amplitude division

d.

Discrete multitone

ANS: D

PTS: 1

25.
____ is a technology that allows a high-speed data signal to traverse a standard copper-based telephone line.
a.

DSL

c.

EIA-232F

b.

RS-232

d.

FireWire

ANS: A
26.

PTS: 1
Chip spreading codes are ____ bits in length.

a.

32

c.

128

b.

64

d.

256

ANS: B

PTS: 1

27.
____ division multiplexing is a good choice for connecting a number of lower-speed devices that do not transmit data on a continuous basis to a remote computer system.
a.

Statistical time

c.

Discrete tone

b.

Time

d.

Frequency

ANS: A

PTS: 1

28.
____ division multiplexing is a good technique for transmitting multiple concurrent signals over a fiber-optic line.
a.

Statistical time

c.

Frequency

b.

Synchronous time

d.

Wavelength

ANS: D

PTS: 1

29.
____ technology is a unique form of multiplexing in that all the subchannels multiplexed together are intended for one user.
a.

Time division

c.

Frequency division

b.

Discrete multitone

d.

Code division

ANS: B

PTS: 1

30.
Code division multiplexing can produce system capacities that are ____ times those of frequency division multiplexing systems.
a.
2 to 4
c.
4 to 8
b.

3 to 6

d.

ANS: D

8 to 10

PTS: 1

31.
If a compression technique does lose some of the data as a result of the compression process, then it is referred to as a ____ compression technique.
a.

complete

c.

lossy

b.

random

d.

lossless

ANS: C

PTS: 1

32.
____ replaces any repetitions of the same bit or byte that occur in a sequence of data with a single occurrence of the bit/byte and a run count, or simply with a run count.
a.

Run-length encoding

c.

Random compression

b.

Lossy compression

d.

Full encoding

ANS: A

PTS: 1

33.
A technique that can be used to compress data when a ____ compression is necessary is the Lempel-Ziv technique.
a.

random

c.

lossy

b.

run-length

d.

lossless

ANS: D

PTS: 1

34.
____, which is an abbreviation for MPEG (Moving Picture Experts Group) Audio
Layer-3, is a common form of audio compression.
a.

MPEG

c.

MP3

b.

GIF

d.

JPEG

ANS: C
35.

PTS: 1
______ is a technique that is very commonly used to compress video images.

a.

JPEG

c.

MP3

b.

MPEG

d.

AAA

ANS: A
36.
compression.

PTS: 1
MPEG-1 and MPEG-2—or simply MPEG—are common examples of ____

a.

wavelength encoding

c.

code division

b.

differential encoding

d.

frequency encoding

ANS: B
37.
systems.
a.
TDM
b.

PTS: 1
Discrete multitone (DMT) is a multiplexing techinque commonly found in _______
c.
d.

DSL

ANS: B

ATM microwave PTS: 1

COMPLETION
1.
The technique of transmitting multiple signals over a single medium is
____________________.
ANS: multiplexing
PTS: 1
2.
A(n) ____________________ is an assigned set of frequencies that is used to transmit the user’s signal.
ANS: channel
PTS: 1
3.
In general, the device that accepts input from one or more users is called the
____________________.
ANS: multiplexor
PTS: 1
4.
To keep one signal from interfering with another signal, a set of unused frequencies called a(n) ____________________ is usually inserted between the two signals, to provide a form of insulation. ANS: guard band
PTS: 1
5.
In ____________________, the sharing of the medium is accomplished by dividing available transmission time among users.
ANS:
time division multiplexing (TDM) time division multiplexing
TDM
PTS: 1
6.
In ____________________ multiplexing, the frames of the multiplexor’s output stream are divided into 24 separate digitized voice/data channels of 64 kbps each.

ANS: T-1
PTS: 1
7.
Synchronous Optical Network (SONET) and ____________________, are powerful standards for multiplexing data streams over a single medium.
ANS:
Synchronous Digital Hierarchy (SDH)
Synchronous Digital Hierarchy
SDH
PTS: 1
8.
____________________, and Synchronous Digital Hierarchy (SDH) are two almost identical standards for the high-bandwidth transmission of a wide range of data types over fiber-optic cable. ANS:
Synchronous Optical Network (SONET)
Synchronous Optical Network
SONET
PTS: 1
9.
A T-1 telecommunications line uses a multiplexing technique termed
____________________, which provides for the multiplexing of up to 24 separate channels at a total speed of 1.544 Mbps.
ANS: DS-1 signaling
PTS: 1
10.
Each STS level supports a particular data rate and is supported by a physical specification called a(n) ____________________.
ANS:
optical carrier (OC) optical carrier
OC
PTS: 1
11.
____________________, transmits data only from active users and does not transmit empty time slots.
ANS:
Statistical time division multiplexing (Stat TDM)
Statistical time division multiplexing
Stat TDM

PTS: 1
12.
In Stat TDM, the ____________________, provides information that the receiving multiplexor can use to detect transmission errors within the frame.
ANS:
frame check sequence (FCS) frame check sequence
FCS
PTS: 1
13.
The inability of a single fiber-optic line to meet users’ needs is called
____________________.
ANS: fiber exhaust
PTS: 1
14.
In WDM, the wavelength of each differently colored laser is called the
____________________.
ANS: lambda
PTS: 1
15.
When WDM can support a large number of lambdas, it is often called
____________________.
ANS: dense wavelength division multiplexing (DWDM) dense wavelength division multiplexing
DWDM
PTS: 1
16.
____________________ is a multiplexing technique commonly found in digital subscriber line (DSL) systems.
ANS:
Discrete multitone (DMT)
Discrete multitone
DMT
PTS: 1
17.
____________________ is a modulation technique that involves a four-bit code in which eight phase angles have a single amplitude, and four phase angles have double amplitudes.
ANS:
Quadrature amplitude modulation (QAM)
Quadrature amplitude modulation

QAM
PTS: 1
18.
____________________ is a relatively new technology that has been used extensively by both the military and cellular telephone companies.
ANS:
Code division multiplexing (CDM)
Code division multiplexing
CDM
PTS: 1
19.
technology.

Code division multiplexing uses ____________________ spread spectrum

ANS: direct sequence
PTS: 1
20.

____________________ are the codes assigned to users in CDM.

ANS: Chip spreading codes
PTS: 1
21.
____________________ is the process of taking data and somehow packing more of it into the same space.
ANS: Compression
PTS: 1
22.
compression.

With a(n) ____________________ compression technique, no data is lost due to

ANS: lossless
PTS: 1
23.
One of the more common and simpler examples of lossless compression is
____________________-length encoding.
ANS: run
PTS: 1
24.
Audio engineers compress music through techniques called perceptual noise shaping, or ____________________.
ANS: perceptual encoding

PTS: 1
ESSAY
1.

What is the difference between a multiplexor and a demultiplexor?

ANS:
In general, the device that accepts input from one or more users is called the multiplexor. The device that is attached to the receiving end of the medium and splits off each signal to deliver it to the appropriate receiver is called the second multiplexor, or demultiplexor. In all frequency division multiplexing systems, the multiplexor accepts input from the user(s), converts the data streams to analog signals using either fixed or dynamically assigned frequencies, and transmits the combined analog signals over a medium that has a wide enough bandwidth to support the total range of all the assigned frequencies. The demultiplexor then accepts the combined analog signals, separates out one or more of the individual analog signals, and delivers these to the appropriate user(s).
PTS: 1
2.

How does time division multiplexing work?

ANS:
Suppose an instructor in a classroom poses a controversial question to students. In response, a number of hands shoot up, and the instructor calls on each student, one at a time. It is the instructor’s responsibility to make sure that only one student talks at any given moment, so that each individual’s response is heard. In a relatively crude way, the instructor is a time division multiplexor, giving each user (student) a moment in time to transmit data (express an opinion to the rest of the class). In a similar fashion, a time division multiplexor calls on one input device after another, giving each device a turn at transmitting its data over a high-speed line. Suppose two users, A and B, wish to transmit data over a shared medium to a distant computer. We can create a rather simple time division multiplexing scheme by allowing user A to transmit during the first second, then user B during the following second, followed again by user A during the third second, and so on.
PTS: 1
3.

How does T-1 multiplexing work?

ANS:
In T-1 multiplexing, the frames of the T-1 multiplexor’s output stream are divided into 24 separate digitized voice/data channels of 64 kbps each. Users who wish to use all 24 channels are using a full
T-1, while other users who need to use only part of the 24 channels may request a fractional T-1. The
T-1 multiplexed stream is a continuous repetition of frames. Each frame consists of 1 byte from each of the 24 channels (users) plus 1 synchronization bit. Thus, data from the first user is followed by the data from the second user, and so on, until data from the 24th user is once again followed by data from the first user. If one of the 24 input sources has no data to transmit, the space within the frame is still allocated to that input source. The input data from a maximum of 24 devices is assigned to fixed intervals. Each device can transmit only during that fixed interval. If a device has no significant data to transmit, the time slot is still assigned to that device, and data such as blanks or zeros are transmitted.
PTS: 1
4.

How does Wavelength division multiplexing work?

ANS:
The technique assigns a uniquely colored laser to each input source and combines the multiple optical signals of the input sources so that they can be amplified as a group and transported over a single fiber.
It is interesting to note that because of the properties of the signals and glass fiber, plus the nature of light itself, each signal carried on the fiber can be transmitted at a different rate from the other signals.
This means that a single fiber-optic line can support simultaneous transmission speeds such as 51.84
Mbps, 155.52 Mbps, 622.08 Mbps, and 2.488 Gbps (which, incidentally, are multiples of T-1 speeds and are defined as OC-1, OC-3, OC-12, and OC-48, the optical carrier specifications for high-speed fiber-optic lines). In addition, a single fiber-optic line can support a number of different transmission formats such as SONET, Asynchronous Transfer Mode (ATM), and others, in various combinations.
PTS: 1
5.

What are the major disadvantages of frequency division multiplexing?

ANS:
Frequency division multiplexing suffers from two major disadvantages. The first disadvantage is found in computer-based systems that multiplex multiple channels over a single medium. Because the frequencies are usually statically assigned, devices that do not have anything to transmit are still assigned frequencies, and thus bandwidth is wasted. The second disadvantage of frequency division multiplexing is due to the fact that the technique uses analog signals, and analog signals are more susceptible to noise disruption than digital signals. Nonetheless, many different types of applications
(such as television and radio) use frequency division multiplexing because of its simplicity, and the technique is probably going to be with us for a long time.
PTS: 1

Chapter 6: Errors, Error Detection, and Error Control
TRUE/FALSE
1.
Because white noise is relatively continuous, it can be reduced significantly but never completely eliminated.
ANS: T
2.
ANS: T

PTS: 1
White noise is dependent on the temperature of the medium.
PTS: 1

3.
If the impulse spike interferes with an analog signal, removing it without affecting the original signal is extremely easy.
ANS: F

PTS: 1

4.
If impulse noise interferes with a digital signal, often the original digital signal cannot be recognized and recovered.
ANS: F
5.

PTS: 1
Noise is a problem for both analog and digital signals.

ANS: T

PTS: 1

6.
Telephone signal crosstalk was a more common problem before telephone companies used fiber-optic cables and other well-shielded wires.
ANS: T
7.
ANS: F

PTS: 1
Echo error rarely occurs at junctions where wires are connected.
PTS: 1

8.
If jitter becomes too great, correcting it can require the transmitting devices to speed up their transmission rates.
ANS: F
9.
ANS: F

PTS: 1
Attenuation can be eliminated with the use of repeaters for analog systems.
PTS: 1

10.
An unfortunate side effect of noise during a transmission is that the transmitting station has to slow down its transmission rate.
ANS: T

PTS: 1

11.
Installing special filters for analog signals and digital signal regeneration for digital signals helps in preventing white noise.
ANS: T
12.
ANS: T
13.
ANS: F
14.
polynomial.
ANS: T
15.
ANS: T
16.
ANS: T
17.

PTS: 1
TCP performs error detection at the end points of the connection.
PTS: 1
Simple parity can detect only an even number of erroneous bits per character.
PTS: 1
The CRC error-detection method treats the packet of data to be transmitted as a large
PTS: 1
The CRC method is almost foolproof.
PTS: 1
Returning a message was one of the first error-control techniques developed.
PTS: 1
NAK represents a positive acknowledgment.

ANS: F
18.

PTS: 1
Sliding window protocols have been around since the 1970s.

ANS: T
19.

PTS: 1
When a parity bit is assigned to ASCII, the Hamming distance becomes 4.

ANS: F

PTS: 1

20.
In a stop-and-wait error control system, a receiver may acknowledge multiple packets with a single ACK.
ANS: F

PTS: 1

21.
In a sliding-winow error control system, a receiver may acknowledge multiple packets with a single ACK.
ANS: T

PTS: 1

MULTIPLE CHOICE
1.

White noise is also called thermal noise or ____ noise.

a.

crosstalk

c.

Gaussian

b.

jitter

d.

spike

ANS: C
2.

PTS: 1
Impulse noise is also known as ____.

a.

noise spike

c.

attenuation

b.

jitter

d.

crosstalk

ANS: A
3.

PTS: 1
Typically, impulse noise is a(n) ____ burst of energy.

a.

digital

c.

binary

b.

analog

d.

logical

ANS: B

PTS: 1

4.
High humidity and wet weather can cause an increase in electrical ____ over a telephone system.
a.

compression

c.

jitter

b.

attenuation

d.

crosstalk

ANS: D

PTS: 1

a.

5.
To minimize the effect of echo, a device called a(n) ____ can be attached to a line. echo suppressor
c.
amplifier

b.

repeater

d.

ANS: A

hub

PTS: 1

6.
____ is the result of small timing irregularities that become magnified during the transmission of digital signals as the signals are passed from one device to another.
a.

White noise

c.

Attenuation

b.

Jitter

d.

Echo

ANS: B

PTS: 1

7.
Causes of jitter can include electromagnetic interference, ____, passing the signal through too many repeaters, and the use of lower-quality equipment.
a.

coding

c.

compression

b.

sampling

d.

crosstalk

ANS: D

PTS: 1

8.
____ is not necessarily a form of error, but can indirectly lead to an increase in errors affecting the transmitted signal.
a.

Impulse noise

c.

Attenuation

b.

Crosstalk

d.

White noise

ANS: C

PTS: 1

9.
____ means that if the transmitting modem sends data and the data arrives garbled, the receiving modem may ask the transmitting modem to fall back to a slower transmission speed.
a.

Impulse negotiation

c.

Attenuation

b.

Fallback negotiation

d.

Downlink

ANS: B

PTS: 1

10.
Twisted pair Category 5e/6 cable should not be longer than the recommended 100meter (300-foot) distance when it’s transmitting at ____ Mbps.
a.

100

c.

500

b.

250

d.

1000

ANS: A
11.

PTS: 1
Installing proper shielding on cables prevents ____.

a.

white noise

c.

attenuation

b.

impulse noise

d.

crosstalk

ANS: D

PTS: 1

12.
Error detection can be performed in several places within a communications model.
One of the most common places is the TCP/IP ____ layer.
a.
network
c.
network access/data link
b.

application

ANS: C
13.
connections.

d.

physical

PTS: 1
The most basic error-detection techniques are parity checks, which are used with ____

a.

synchronous

c.

statistical

b.

asynchronous

d.

fiber-optic

ANS: B
14.

PTS: 1
With ____ parity, the 0 or 1 added to the string produces an even number of binary 1s.

a.

even

c.

longitudinal

b.

odd

d.

binary

ANS: A
15.

PTS: 1
Isolated single-bit errors occur ____ percent of the time.

a.

30 to 40

c.

50 to 60

b.

40 to 50

d.

60 to 70

ANS: C

PTS: 1

16.

Error bursts occur ____ percent of the time.

a.

2 to 5

c.

8 to 10

b.

5 to 10

d.

10 to 20

ANS: D
17.

PTS: 1
Longitudinal parity is sometimes called longitudinal redundancy check or ____ parity.

a.

vertical

c.

random

b.

horizontal

d.

binary

ANS: B
18.

PTS: 1
The cyclic redundancy checksum (CRC) is also called ____.

a.

horizontal parity

c.

bit parity

b.

vertical cyclic parity

d.

cyclic checksum

ANS: D
19.
a.

5

PTS: 1
CRC-____ is found in Ethernet LANs.
c.

32

b.

12

d.

ANS: C

64

PTS: 1

20.
____ for error control is becoming a mode of operation for some modern wide area network transmission techniques.
a.

Returning a message

c.

Correcting the error

b.

Doing nothing

d.

Fixing the error

ANS: B
21.

PTS: 1
____ is offered by telephone companies to transfer data over wide areas.

a.

RS-232

c.

SSL

b.

EIA-232F

d.

Frame Relay

ANS: D
22.

PTS: 1
____ cable is the medium least prone to generating errors.

a.

Fiber-optic

c.

Twisted-pair

b.

Coaxial

d.

Copper-based

ANS: A
23.

PTS: 1
____ is probably the most common form of error control.

a.

Do nothing

b.

Correct the error without retransmission

c.

Sending a message back to the transmitter

d.

Correct the error with retransmission

ANS: C

PTS: 1

24.
____ error control is a technique usually associated with the Stop-and-wait flow control protocol.
a.

Stop-and-wait

c.

Sliding window

b.

Timeout

d.

ACK

ANS: A

PTS: 1

25.
When working with stop-and-wait error control, the amount of time a station waits before retransmitting a packet is called ____.
a.

stop time

c.

NAK time

b.

ACK time

d.

timeout

ANS: D

PTS: 1

26.
____ is a flow control scheme that allows a station to transmit a number of data packets at one time before receiving some form of acknowledgment.
a.
Stop-and-wait
c.
Timeout
b.

Sliding window

ANS: B

d.

ACK window

PTS: 1

27.
With the sliding window protocol, a station that had a maximum window size of 7 could transmit only ____ data packets at one time before it had to stop and wait for an acknowledgment. a.

5

c.

7

b.

6

d.

8

ANS: C

PTS: 1

28.
A ____ protocol’s function is simply to inform the transmitter what piece of data is expected next.
a.

CRC-16

c.

stop-and-wait

b.

CRC-32

d.

sliding window

ANS: D

PTS: 1

29.
For a receiver to be able to fix an error—in a process called ____—redundant information must be present so that the receiver knows which bit or bits are in error and what their original values were.
a.

forward error correction

c.

backward error correction

b.

forward error detection

d.

backward error detection

ANS: A
30.

PTS: 1
If a receiver correctly receives packets 2, 3, and 4, it will respond with a(an) ____ .

a.

ACK 3

c.

ACK 5

b.

ACK 4

d.

NAK

ANS: C

PTS: 1

31.
If a receiver has just received one packet of data with bytes numbered 600 to 700, it will respond immediately with ____.
a.

an ACK of 700

c.

an ACK of 800

b.

an ACK of 701

d.

it will not respond just yet

ANS: B

PTS: 1

COMPLETION
1.
____________________ is a relatively continuous type of noise and is much like the static you hear when a radio is being tuned between two stations.

ANS: White noise
PTS: 1
2.
____________________ is a noncontinuous noise and one of the most difficult errors to detect, because it can occur randomly.
ANS: Impulse noise
PTS: 1
3.

____________________ is an unwanted coupling between two different signal paths.

ANS: Crosstalk
PTS: 1
4.
____________________ is the reflective feedback of a transmitted signal as the signal moves through a medium.
ANS: Echo
PTS: 1
5.
A(n) ____________________ is essentially a filter that allows the signal to pass in one direction only.
ANS: echo suppressor
PTS: 1
6.
When a digital signal is being transmitted, the rises and falls of the signal can start to shift, or become blurry, and thus produce ____________________.
ANS: jitter
PTS: 1
7.
____________________ is the continuous loss of a signal’s strength as it travels though a medium.
ANS: Attenuation
PTS: 1
8.
When a modem first makes a connection with another modem, the two modems participate in ____________________ negotiation.
ANS: fallback
PTS: 1

9.

The simplest error-detection technique is ____________________ parity.

ANS: simple
PTS: 1 parity. 10.

Simple parity comes in two basic forms: even parity and ____________________

ANS: odd
PTS: 1
11.
With ____________________ parity, the 0 or 1 added to the string produces an odd number of binary 1s.
ANS: odd
PTS: 1
12.
____________________ parity tries to solve the main weakness of simple parity— that all even numbers of errors are not detected.
ANS: Longitudinal
PTS: 1
13.
The ____________________ method typically adds 8 to 32 check bits to potentially large data packets and yields an error detection capability approaching 100 percent.
ANS:
cyclic redundancy checksum (CRC) cyclic redundancy checksum
CRC
cyclic checksum
PTS: 1
14.
A(n) _________________________ is an industry-approved bit string that is used to create the cyclic checksum remainder.
ANS: generating polynomial
PTS: 1
15.
Once an error in the received data transmission stream is detected, the action that the receiver takes is called ____________________.
ANS: error control
PTS: 1

16.
____________________ is a process that keeps a transmitter from sending too much data to a receiver.
ANS: Flow control
PTS: 1
17.

Sliding window error control is based on the ____________________ protocol.

ANS: sliding window
PTS: 1
18.
In TCP/IP, if a receiver just received some data and wishes to send data back to the sender, then the receiver should include an ACK with the data it’s about to send. This is called
____________________.
ANS: piggybacking
PTS: 1
19.
A(n) ____________________ code is a specially designed code in which special check bits have been added to data bits such that, if an error occurs during transmission, the receiver may be able to correct the error using the included check and data bits.
ANS: Hamming
PTS: 1
20.
The ____________________ of a code is the smallest number of bits by which character codes differ.
ANS: Hamming distance
PTS: 1

ESSAY
1.

List and briefly explain some error-prevention techniques.

ANS:
You can prevent the occurrence of many types of transmission errors by applying proper errorprevention techniques, including those listed below:
* Install wiring with the proper shielding to reduce electromagnetic interference and crosstalk.
* Use telephone line conditioning or equalization (provided by the telephone company), in which filters are used to help reduce signal irregularities. For an additional charge, the telephone company will provide various levels of conditioning to leased lines. This conditioning provides a quieter line, which minimizes data transmission errors.
* Replace older equipment with more modern, digital equipment; although initially expensive, this technique is often the most cost-effective way to minimize transmission errors in the long run.
* Use the proper number of digital repeaters and analog amplifiers to increase signal strength, thus decreasing the probability of errors.

* Observe the stated capacities of a medium, and, to reduce the possibility of errors, avoid pushing transmission speeds beyond their recommended limits.
PTS: 1
2.

How does simple parity work?

ANS:
If the 7-bit ASCII character set is used, a parity bit is added as the eighth bit. Suppose, for example, that the character “k”—which is 1101011 in binary—is transmitted and even parity is being applied. In this case, a parity bit of 1 would be added to the end of the bit stream, as follows: 11010111. There is now an even number (six) of 1s. (If odd parity were used, a 0 would be added at the end, resulting in
11010110.)
Now, if a transmission error causes one of the bits to be flipped (the value is erroneously interpreted as a 0 instead of a 1, or vice versa), the error can be detected if the receiver understands that it needs to check for even parity. Returning to the example of the character “k” sent with even parity, if you send
11010111 but 01010111 is received, the receiver will count the 1s, see that there is an odd number, and know there is an error. What happens if 11010111 with even parity is sent and two bits are corrupted?
For example, 00010111 is received. Will an error be detected? The answer is no, an error will not be detected, because the number of 1s is still even.
PTS: 1
3.

How does longitudinal parity work?

ANS:
The first step of this parity scheme involves grouping individual characters together in a block. Each character (also called a row) in the block has its own parity bit. In addition, after a certain number of characters are sent, a row of parity bits, or a block character check, is also sent. Each parity bit in this last row is a parity check for all the bits in the column above it. If one bit is altered in Row 1, the parity bit at the end of Row 1 signals an error. In addition, the parity bit for the corresponding column also signals an error. If two bits in Row 1 are flipped, the Row 1 parity check will not signal an error, but two column parity checks will signal errors. This is how longitudinal parity is able to detect more errors than simple parity. Note, however, that if two bits are flipped in Row 1 and two bits are flipped in Row 2, and the errors occur in the same column, no errors will be detected.
PTS: 1
4.

How does the cyclic redundancy checksum work?

ANS:
The CRC error-detection method treats the packet of data to be transmitted (the message) as a large polynomial. The rightmost bit of the data becomes the x0 term, the next data bit to the left is the x1 term, and so on. When a bit in the message is 1, the corresponding polynomial term is included.
The transmitter takes this message polynomial and, using polynomial arithmetic, divides it by a given generating polynomial, and produces a quotient and a remainder. The quotient is discarded, but the remainder (in bit form) is appended to the end of the original message polynomial, and this combined unit is transmitted over the medium. When the data plus remainder arrive at the destination, the same generating polynomial is used to detect an error.

The receiver divides the incoming data (the original message polynomial plus the remainder) by the exact same generating polynomial that was used by the transmitter. If no errors were introduced during data transmission, the division should produce a remainder of zero. If an error was introduced during transmission, the arriving original message polynomial plus the remainder will not divide evenly by the generating polynomial and will produce a nonzero remainder, signaling an error condition.
PTS: 1
5.

How does frame relay control errors?

ANS:
Frame relay, which has only been in existence since 1994 and is offered by telephone companies to transfer data over wide areas, supports the “do nothing” approach to error control. If a data frame arrives at a frame relay switch and an error is detected after the cyclic checksum is performed, the frame is simply discarded. The rationale behind this action is twofold. Frame relay networks are created primarily of fiber-optic cable. Because fiber-optic cable is the medium least prone to generating errors, it is assumed that the rate of errors is low and that error control is unnecessary. If a frame is in error and is discarded, frame relay assumes that either the transport layer or the higher-layer application that is using frame relay to transmit data will keep track of the frames and will notice that a frame has been discarded. It would then be the responsibility of the application to request that the dropped frame be retransmitted. Consider the example in which a company has a database application that sends database records across the country between two corporate locations. The database application (at the application layer) is using frame relay at the data link layer to transfer the actual records. If a record or part of a record is dropped by frame relay because of a transmission error, frame relay does not inform the application. Instead, the database application has to keep track of all records sent and received, and if one record does not arrive at the destination, the database application has to ask for a retransmission.
PTS: 1

Chapter 7: Local Area Networks: The Basics
TRUE/FALSE
1.
Perhaps the strongest advantage of a local area network is its capability of allowing users to share hardware and software resources.
ANS: T
2.
ANS: F

PTS: 1
The local area network first appeared in the 1950s.
PTS: 1

3.
By keeping all of the application on the server, the network can control access to the software and can reduce the amount of disk storage required on each user’s workstation for this application. ANS: T
4.

PTS: 1
A local area network cannot interface with other local area networks.

ANS: F

PTS: 1

5.
Most modern local area networks provide the capabilities of transferring video images and video streams.
ANS: T

PTS: 1

6.
One of the biggest advantages of local area networks is their ability to share resources in an economical and efficient manner.
ANS: T
7.
ANS: F

PTS: 1
A local area network is only as strong as its strongest link.
PTS: 1

8.
The bus/tree topology was the first physical design used when local area networks became commercially available in the late 1970s.
ANS: T bus. 9.

ANS: F

PTS: 1
Baseband signaling typically uses multiple digital signals to transmit data over the
PTS: 1

10.
All bus networks share a major disadvantage: In general, it is difficult to add a new workstation if no tap currently exists.
ANS: T
11.
ANS: F
12.
ANS: T small. 13.

ANS: F
14.
protocol.
ANS: F
15.
ANS: T

PTS: 1
Hubs support only twisted pair cable for interhub connection.
PTS: 1
With the CSMA/CD protocol, only one workstation at a time can transmit.
PTS: 1
If the network is experiencing a high amount of traffic, the chances for collision are
PTS: 1
The most popular example of a contention-based protocol is the token-passing
PTS: 1
The hub, in most applications, has been replaced with the switch.
PTS: 1

16.
ANS: T
17.
ANS: T

A hub is a simple device that requires virtually no overhead to operate.
PTS: 1
Most switches are transparent, which means they learn by themselves.
PTS: 1

18.
Switches can significantly decrease interconnection traffic and increase the throughput of the interconnected networks or segments.
ANS: T
19.
ANS: F
20.
ANS: T
21.
connection.
ANS: F

PTS: 1
A hub is designed to perform much faster than a switch.
PTS: 1
A cut-through switch does not store a data frame and then forward it.
PTS: 1
In a shared segment network, each workstation then has a private or dedicated
PTS: 1

22.
Switches can be used in combination with routers to further isolate traffic segments in a local area network.
ANS: T

PTS: 1

23.
The logical link control sublayer defines the layout or format of the data frame, simply called the frame.
ANS: F

PTS: 1

24.
Three of the most popular local area network systems are Ethernet, IBM Token Ring, and Wireless Ethernet.
ANS: T

PTS: 1

25.
The term “Base”, such as in 100BaseT, is an abbreviation for baseband signals using a
Manchester encoding.
ANS: T

PTS: 1

26.
Using coaxial cable to transmit analog signals, 10Broad36 can transmit data at 10
Mbps for a maximum segment distance of 3600 meters.
ANS: T

PTS: 1

27.
The Fast Ethernet standards are based on 1000-Mbps transmission speeds, or 1 gigabit
(1 billion bits) per second.
ANS: F
28.
ANS: T
29.
ANS: F

PTS: 1
1000BaseSX was the first Gigabit Ethernet standard.
PTS: 1
1000BaseT is capable of using only the Category 7 cable specification.
PTS: 1

30.
“Wireless Ethernet” is a local area network that is not based primarily on physical wiring but uses wireless transmissions between workstations.
ANS: T
31.
ANS: T

PTS: 1
A rule known as the 5-4-3 rule helps guide the design of a shared-access Ethernet.
PTS: 1

32.
The SOHO LAN (small office home office) is one the fastest growing segments of the networking market.
ANS: T

PTS: 1

33.
In the case of CSMA/CD local area networks, as the networks grow in size, their performance increases.
ANS: F
34.
ANS: F

PTS: 1
Wireless local area networks are typically found in seven basic configurations.
PTS: 1

35.
In the wireless LAN ad hoc layout configuration, each user device communicates directly with the other user devices.
ANS: T
36.
ANS: F

PTS: 1
The 802.11 specification defined six different types of physical layer connections.
PTS: 1

MULTIPLE CHOICE
1.

Early local area networks transmitted data at only ____ million bits per second.

a.

1

c.

100

b.

10

d.

1000

ANS: B

PTS: 1

2.
A local area network performs file serving when it’s connected to a workstation with a large storage disk drive that acts as a central storage repository, or ____ server.
a.
file
c.
database
b.

printer

d.

ANS: A

application

PTS: 1

3.
The local area network software called a ____ server provides workstations with the authorization to access a particular printer, accepts and queues prints jobs, prints cover sheets, and allows users access to the job queue for routine administrative functions.
a.

application

c.

file

b.

database

d.

print

ANS: D
4.

PTS: 1
The ____ topology consists of a simple cable, or bus, to which all devices attach.

a.

bus/tree

c.

ring star

b.

token ring

d.

star

ANS: A
____.

5.

PTS: 1
In a bus/tree topology, connecting to the cable requires a simple device called a(n)

a.

hub

c.

tap

b.

router

d.

echo suppressor

ANS: C

PTS: 1

6.
Two different signaling technologies can be used with a bus network: baseband signaling and ____ signaling.
a.

multiband

c.

uniband

b.

broadband

d.

singleband

ANS: B

PTS: 1

7.
More complex bus topologies consisting of multiple interconnected cable segments are termed ____.
a.

tokens

c.

rings

b.

stars

d.

trees

ANS: D
8.

PTS: 1
The most popular configuration for a local area network is the ____ topology.

a.

ring

c.

bus

b.

star-wired bus

d.

tree

ANS: B

PTS: 1

9.
The ____ design of a network determines how the data moves around the network from workstation to workstation.
a.
electrical
c.
physical
b.

data

d.

ANS: D
10.

logical

PTS: 1
____ cabling has become the preferred medium for star-wired bus topologies.

a.

Twisted pair

c.

Fiber-optic

b.

Coaxial

d.

FDDI

ANS: A

PTS: 1

11.
When two or more hubs are interconnected and a workstation transmits data, all the workstations connected to all the hubs receive the data. This is an example of a(n) ____.
a.

wireless topology

c.

shared network

b.

switched network

d.

FDDI topology

ANS: C

PTS: 1

12.
A local area network that is not based primarily on physical wiring but uses wireless transmissions between workstations is a(n) ____.
a.

FDDI

c.

token ring

b.

wireless LAN

d.

MAU

ANS: B

PTS: 1

13.
The ____ is essentially the interface device between the wireless user device and the wired local area network.
a.

wireless server

c.

NIC

b.

wireless workstation

d.

access point

ANS: D

PTS: 1

14.
In the ____ layout configuration, multiple cells are supported by multiple access points, as in a cellular telephone network.
a.

multiple-cell

c.

one-cell

b.

single-cell

d.

unique-cell

ANS: A
15.

PTS: 1
The wireless LAN term for a collection of multiple Basic Service Sets is ____.

a.

Multiple Service Set
(MSS)

c.

Extended Service Set (ESS)

b.

Basic Service Set (BSS)

d.

Complex Service Set (CSS)

ANS: C
16.

PTS: 1
In the ____, or ad hoc, layouts configuration, there is no access point at the center of a

cell.
a.

peer-to-peer

c.

single-cell

b.

multiple-cell

d.

random-cell

ANS: A

PTS: 1

17.
____, a European standard, is capable of transmitting data at a theoretical 54 Mbps using the 5-GHz frequency range.
a.

WiMAX

c.

WiLAN/3

b.

HiperLAN/2

d.

WiFi/8

ANS: B
18.
area network.

PTS: 1
A(n) ____ protocol is the software that allows a workstation to place data onto a local

a.

error control

c.

medium access control

b.

noise control

d.

flow control

ANS: C
19.

PTS: 1
The most popular contention-based protocol is ____.

a.

token ring

b.

round-robin

c.

carrier sense multiple access with collision avoidance (CSMA/CA)

d.

carrier sense multiple access with collision detection (CSMA/CD)

ANS: D
20.

PTS: 1
The interval during which the signals propagate down the bus and back is the ____.

a.

exponential backoff

c.

attenuation

b.

collision window

d.

bounce window

ANS: B

PTS: 1

21.
In CSMA/CA, the amount of time a device is made to wait before it can transmit is called the ____.
a.

frame space (FS)

c.

interframe space (IFS)

b.

frame time (FT)

d.

intraframe time (IFT)

ANS: C

PTS: 1

22.
The ____ sublayer contains a header, computer (physical) addresses, error-detection codes, and control information.

a.

logical link control (LLC)

c.

medium access control (MAC)

b.

logical flow control
(LFC)

d.

physical link control (PLC)

ANS: C

PTS: 1

23.
The ____ sublayer is primarily responsible for logical addressing and providing error control and flow control information.
a.

medium access control
(MAC)

c.

medium physical control (MPC)

b.

physical access control
(PAC)

d.

logical link control (LLC)

ANS: D

PTS: 1

24.
____ was the first commercially available local area network system and remains, without a doubt, the most popular local area network system today.
a.

Ethernet

c.

FDDI

b.

IBM Token Ring

d.

Wireless Ethernet

ANS: A
25.

PTS: 1
The ____ standard was one of the first Ethernet standards approved.

a.

10Broad36

c.

100BaseTX

b.

10Base5

d.

100BaseT4

ANS: B

PTS: 1

26.
____ was a system designed for twisted pair wiring, but with only a 1-Mbps data transfer rate for 500 meters.
a.

10BaseT

c.

100BaseTX

b.

10Broad36

d.

1Base5

ANS: D

PTS: 1

27.
A ____ system transmits 10-Mbps baseband (digital) signals over twisted pair for a maximum of 100 meters per segment length.
a.

1Base5

c.

10BaseT

b.

10Broad36

d.

100BaseTX

ANS: C
28.

PTS: 1
IEEE created the 100-Mbps Ethernet 802.3u protocol also called ____ Ethernet.

a.

Fast

c.

Terabit

b.

Gigabit

d.

FDDI

ANS: A

PTS: 1

a.

29.
____ was the standard created for fiber-optic systems.
1Base5
c.
100BaseTX

b.

10BaseTX

ANS: D
30.

d.

100BaseFX

PTS: 1
The IEEE 802.3z standards are also known as ____ Ethernet.

a.

Switch

c.

Gigabit

b.

Fast

d.

Terabit

ANS: C
31.

PTS: 1
With ____, you can send electrical power over the Ethernet connection.

a.

1Base5

c.

10GBase-fiber

b.

power over Ethernet
(PoE)

d.

FDDI

ANS: B
32.

PTS: 1
The IEEE ____ standard is said to be capable of 100 Mbps wireless transmissions.

a.

802.11a

c.

802.11g

b.

802.11b

d.

802.11n

ANS: D

PTS: 1

33.
The ____ rule states that between any two nodes on a network, there can be a maximum of only five segments (the sections between repeaters), connected through four repeaters, and only three of the five segments may contain user connections.
a.

2-4-3

c.

5-4-3

b.

3-4-5

d.

6-5-3

ANS: C
34.

PTS: 1
The ____ LAN is geared toward the small office or home office.

a.

SMART

c.

GRID

b.

SOHO

d.

Gigabit

ANS: B
35.

PTS: 1
The ____ is used to connect local area networks to wide area networks.

a.

hub

c.

router

b.

repeater

d.

bridge

ANS: C

PTS: 1

36.
A ____ is a device that interconnects two or more workstations in a star-wired bus local area network and immediately retransmits the data it receives from any workstation out to all other workstations connected.
a.
hub
c.
router
b.

switch

d.

ANS: A a filter.

37.

repeater

PTS: 1
A ____ is a device that interconnects two segments of local area networks and acts as

a.

hub

c.

router

b.

switch

d.

satellite

ANS: B
38.

PTS: 1
A transparent bridge creates the internal port table by using a form of ____.

a.

forward learning

c.

backward learning

b.

backward correction

d.

forward correction

ANS: C
39.

PTS: 1
The switch operates in place of a ____.

a.

repeater

c.

router

b.

bridge

d.

hub

ANS: D

PTS: 1

40.
In a ____ architecture, the data frame begins to exit the switch almost as soon as it begins to enter the switch.
a.

forward

c.

cut-through

b.

backward

d.

random-propagation

ANS: C
Mbps.

41.

PTS: 1
If a switch has eight 100-Mbps ports, the backplane has to support a total of ____

a.

200

c.

600

b.

400

d.

800

ANS: D

PTS: 1

42.
Depending on user requirements, a switch can interconnect two different types of
CSMA/CD network segments: ____ segments and dedicated segments.
a.

shared

c.

local

b.

remote

d.

distributed

ANS: A

PTS: 1

43.
In ____ segment networks, a switch may be directly connected to a workstation, and the switch connects to the hub.
a.
shared
c.
distributed
b.

dedicated

ANS: B

d.

remote

PTS: 1

44.
One of the more interesting applications for a dedicated segment network and a switch is creating a ____.
a.

virtual LAN

c.

shared LAN

b.

dedicated LAN

d.

local LAN

ANS: A

PTS: 1

45.
A relatively new standard, IEEE ____, was designed to allow multiple devices to intercommunicate and work together to create a virtual LAN.
a.

802.1a

c.

802.1P

b.

802.1g

d.

802.1Q

ANS: D

PTS: 1

46.
Whether shared or dedicated segments are involved, the primary goal of a(n) ____ is to isolate a particular pattern of traffic from other patterns of traffic or from the remainder of the network. a.

hub

c.

repeater

b.

switch

d.

amplifier

ANS: B

PTS: 1

COMPLETION
1.
A(n) _________________________ is a communications network that interconnects a variety of data communications devices within a small geographic area and broadcasts data at high data transfer rates.
ANS:
local area network (LAN) local area network
LAN
LAN (local area network)
PTS: 1
2.
A(n) ____________________ is the physical (hardware) layout used to interconnect the workstations within a local area network.
ANS: topology

PTS: 1
3.
The tap is a(n) ____________________, as it does not alter the signal and does not require electricity to operate.
ANS: passive device
PTS: 1
4.
The ______________________________ is an electronic device that performs the necessary signal conversions and protocol operations that allow the workstation to send and receive data on the network.
ANS:
network interface card (NIC) network interface card
NIC
NIC (network interface card)
PTS: 1
5.
____________________ means that when the signal is transmitted from a given workstation, the signal propagates away from the source in both directions on the cable.
ANS: Bidirectional
PTS: 1
6.
The ____________________ design refers to the pattern formed by the locations of the elements of the network, as it would appear if drawn on a sheet of paper.
ANS: physical
PTS: 1
7.
A(n) ____________________ is the wireless LAN component that communicates with the wireless user device.
ANS: access point
PTS: 1
8.
The wireless LAN standards call a single-cell wireless LAN a(n)
_________________________.
ANS:
Basic Service Set (BSS)
Basic Service Set
BSS
BSS (Basic Service Set)
PTS: 1

9.
To promote acceptance, the ____________________ suite of protocols was created to support the many different types of wireless local area networks in existence.
ANS: IEEE 802
PTS: 1
10.

A(n) ____________________ protocol is basically a first-come, first-served protocol.

ANS: contention-based
PTS: 1
11.
A(n) ____________________ occurs when two or more workstations listen to the medium at the same moment, hear nothing, and then transmit their data at the same moment.
ANS: collision
PTS: 1
12.
A(n) ____________________ protocol is one in which you cannot calculate the time at which a workstation will transmit.
ANS: nondeterministic
PTS: 1
13.
The type of algorithm that tries to avoid collisions is called
_____________________________________________.
ANS: carrier sense multiple access with collision avoidance (CSMA/CA) carrier sense multiple access with collision avoidance
CSMA/CA
CSMA/CA (carrier sense multiple access with collision avoidance)
PTS: 1
14.
With the ____________________ algorithm the workstation listens continuously until the medium is free, then transmits immediately.
ANS: 1-persistent
PTS: 1
15.
In IEEE 802.3 standard for CSMA/CD, frames shorter than 64 bytes are considered
____________________, or frame fragments.
ANS: runts
PTS: 1

16.
____________________ (nicknamed Cheapernet) was designed to allow for a lessexpensive network by using less-expensive components.
ANS: 10Base2
PTS: 1
17.
One of the most common standards for broadband (analog) Ethernet was the
____________________ specification.
ANS: 10Broad36
PTS: 1
18.
____________________ was designed to support 100-Mbps baseband signals using two pairs of Category 5 unshielded twisted pair.
ANS: 100BaseTX
PTS: 1
19.
____________________ was created to support older-category wire. Thus it can operate over Category 3 or 4 twisted pair wire, as well as Category 5/5e/6 unshielded twisted pair.
ANS: 100BaseT4
PTS: 1
20.

The ____________________ Ethernet standard is also known as IEEE 802.3ae.

ANS: 10 Gbps
PTS: 1
21.
________________________________________ is a technology in which both the mobile device and the access point have multiple, smart antennae that help to reduce signal interference and reflections.
ANS:
Multiple input multiple output (MIMO)
Multiple input multiple output
MIMO
MIMO (Multiple input multiple output)
PTS: 1
22.
The ____________________ is a device that connects workstations to local area networks and retransmits the incoming frame.
ANS: hub
PTS: 1

23.
The ____________________ allows workstations to connect to LANs and interconnects multiple segments of LANs.
ANS: switch
PTS: 1
24.
A(n) ____________________ is a device that interconnects two local area networks and can use processing power to direct a frame out a particular port, thus reducing the amount of traffic on the network.
ANS: switch
PTS: 1
25.
A(n) ____________________ examines the destination address of a frame and either forwards or does not forward the frame, depending on some address information stored within the bridge. ANS: filter
PTS: 1
26.

The main hardware of the switch is called the ____________________.

ANS: backplane
PTS: 1
27.
If the circuit cards are ____________________, it is possible to insert and remove cards while the power to the unit is still on.
ANS: hot swappable
PTS: 1
28.
In ____________________ segment networks, a switch may be connected to a hub (or several hubs), which then connects multiple workstations.
ANS: shared
PTS: 1
29.
A(n) ____________________ is a logical subgroup within a local area network that is created via switches and software rather than by manually moving wiring from one network device to another. ANS: virtual LAN
VLAN
PTS: 1

30.
The ____________________ allows for a CSMA/CD network to simultaneously transmit and receive data to and from a workstation.
ANS: full-duplex switch
PTS: 1
ESSAY
1.
A local area network (LAN) is a communications network that interconnects a variety of data communications devices within a small geographic area and broadcasts data at high data transfer rates. Expand on this definition by explaining the various terminology used.
ANS:
Several points in this definition merit a closer look. The phrase “data communications devices” covers computers such as personal computers, computer workstations, and mainframe computers, as well as peripheral devices such as disk drives, printers, and modems. Data communications devices could also include items such as motion, smoke, and heat sensors; fire alarms; ventilation systems; and motor speed controls. These latter devices are often found in businesses and manufacturing environments where assembly lines and robots are commonly used.
The next piece of the definition, “within a small geographic area” usually implies that a local area network can be as small as one room, or can extend over multiple rooms, over multiple floors within a building, and even over multiple buildings within a single campus-area. The most common geographic areas, however, are a room or multiple rooms within a single building. Local area networks differ from many other types of networks in that most broadcast their data to many or all of the workstations connected to the network. Thus, if one workstation has data to send to a second workstation, that data is transmitted to other workstations on the network. When data that was not requested arrives at a workstation, it is simply discarded. As you will see a little later, it is now quite common to design a local area network so that all data is not transmitted to all workstations—an enhancement that reduces the amount of traffic on the network.
Lastly, the final phrase of the definition states that local area networks are capable of transmitting data at “high data transfer rates”. While early local area networks transmitted data at only 10 million bits per second, the newest local area networks can transmit data at 10 billion bits per second.
PTS: 1
2.

What are some of the application areas where a LAN can be an effective tool?

ANS:
A local area network can be an effective tool in many application areas. One of the most common application areas is an office environment. A local area network in an office can provide word processing, spreadsheet operations, database functions, electronic mail (e-mail) access, Internet access, electronic appointment scheduling, and graphic image creation capabilities over a wide variety of platforms and to a large number of workstations. Completed documents can be routed to high-quality printers to produce letterheads, graphically designed newsletters, and formal documents.
A second common application area for a local area network is an academic environment. In a laboratory setting, for example, a local area network can provide students with access to the tools necessary to complete homework assignments, send e-mail, and utilize the Internet. In a classroom setting, a local area network can enable professors to deliver tutorials and lessons with high-quality graphics and sound to students. Multiple workstations can be used to provide students with instruction

at their own pace, while the instructor monitors and records each student’s progress at every workstation. A third common application area for a local area network is manufacturing. In fact, modern assembly lines operate exclusively under the control of local area networks. As products move down the assembly line, sensors control position; robots perform mundane, exacting, or dangerous operations; and product subassemblies are inventoried and ordered. The modern automobile assembly line is a technological tour de force, incorporating numerous local area networks and mainframe computers.
PTS: 1
3.

How does a star-wired bus topology work?

ANS:
In a star-wired bus topology, all workstations connect to a central device such as the hub. The hub is a nonintelligent device that simply and immediately retransmits the data it receives from any workstation out to all other workstations (or devices) connected to the hub. All workstations hear the transmitted data, because there is only a single transmission channel, and all workstations are using this one channel to send and receive. Sending data to all workstations and devices generates a lot of traffic but keeps the operation very simple, because there is no routing to any particular workstation.
Thus, with regard to its logical design, the star-wired bus is acting as a bus: when a workstation transmits, all workstations (or devices) immediately receive the data. The network’s physical design, however, is a star, because all the devices are connected to the hub and radiate outward in a starlike (as opposed to linear) pattern.
The hub at the center of star-wired bus topology comes in a variety of designs.They can contain anywhere from two to hundreds of connections, or ports, as they are called. If, for example, you have a hub with 24 ports, and more are desired, it is fairly simple to either interconnect two or more hubs, or purchase a larger hub.
PTS: 1
4.

Briefly explain the evolution of the wireless LAN protocols.

ANS:
Since the introduction of IEEE 802.11, other IEEE wireless LAN protocols have emerged. IEEE
802.11b, which was ratified in September 1999, can transmit data at a theoretical rate of 11 Mbps (due to noise, the actual rate is roughly one-half the theoretical) using 2.4-GHz signals. Many users who had found 802.11’s data rate of 2 Mbps too slow were excited to see 802.11b products hit the market.
Another name for 802.11b (as well as the other 802.11 wireless LAN standards) is Wi-Fi (wireless fidelity). IEEE 802.11g, introduced in 2002, transmits data at a theoretical rate of 54 Mbps using the same 2.4-GHz frequencies used in 802.11b. Also introduced in 2002 was IEEE 802.11a, which is capable of supporting a theoretical rate of 54-Mbps transmissions using the 5-GHz frequency range.
As if all the IEEE protocols were not enough to remember, yet one more protocol for wireless LANs is worth mentioning. HiperLAN/2, a European standard, is also capable of transmitting data at a theoretical 54 Mbps using the 5-GHz frequency range.
The newer wireless protocols do come with some disadvantages. The high 5-GHz frequency ranges used in IEEE 802.11a and HiperLAN/2 require so much power that laptops and portables have trouble delivering these signals for a useful amount of time. Second, the transmission distance for the higher frequency ranges is shorter than for the lower frequency ranges.

PTS: 1
5.

Explain the switch filtering function.

ANS:
As a frame of data moves across the first local area network and enters the switch, the switch examines the source and destination addresses that are stored within the frame. These frame addresses are assigned to the network interface card (NIC) when the NIC is manufactured. (All companies that produce NICs have agreed to use a formula that ensures that every NIC in the world has a unique NIC address.) The switch, using some form of internal logic, determines if a data frame’s destination address belongs to a workstation on the current segment. If it does, the switch does nothing more with the frame, because it is already on the appropriate segment. If the destination address is not an address on the current segment, the switch passes the frame on to the next segment, assuming that the frame is intended for a station on that segment. Additionally, the switch can check for transmission errors in the data by performing a cyclic checksum computation on the frame.
PTS: 1
6.

Explain the cut-through architecture including its advantages and disadvantages.

ANS:
In a cut-through architecture, the data frame begins to exit the switch almost as soon as it begins to enter the switch. In other words, a cut-through switch does not store a data frame and then forward it.
In contrast, a store-and-forward device holds the entire frame for a small amount of time while various fields of the frame are examined, a procedure that diminishes the overall network throughput. The cutthrough capability allows a switch to pass data frames very quickly, thus improving the overall network throughput. The major disadvantage of cut-through architecture is the potential for the device to forward faulty frames. For example, if a frame has been corrupted, a store-and-forward device will input the frame, perform a cyclic checksum, detect the error, and perform some form of error control.
A cut-through device, however, is so fast that it begins forwarding the frame before the cyclic checksum field can be calculated. If there is a cyclic checksum error, it is too late to do anything about it. The frame has already been transmitted. If too many corrupted frames are passed around the network, network integrity suffers.
PTS: 1

Chapter 8: Local Area Networks: Software and Support Systems
TRUE/FALSE
1.
Network operating systems are essential if the network is going to allow multiple users to share resources.
ANS: T
2.
ANS: F
3.

PTS: 1
Users cannot interact directly with the operating system through a shell.
PTS: 1
In reality, a multitasking operating system runs only one program at a time.

ANS: T

PTS: 1

4.
The resources that a network operating system must manage typically include one or more network servers.
ANS: T
5.
ANS: F
6.
ANS: T
7.
ANS: T
8.
ANS: T
9.
ANS: T
10.
ANS: F

PTS: 1
A network operating system does not perform network support functions.
PTS: 1
Microsoft Windows 7 is an example of a desktop operating system.
PTS: 1
NetWare 6 was the last version of Novell’s network operating system.
PTS: 1
A bindery contains the data that pertains only to the server it resides in.
PTS: 1
The design of a tree should ideally be similar to a pyramid.
PTS: 1
NetWare 5 dropped the NDS distributed database of network resources.
PTS: 1

11.
Windows 2008 Server is a network operating system designed to run over a network of microcomputer workstations and provide file sharing and peripheral sharing.
ANS: T
12.
ANS: F
13.
ANS: F

PTS: 1
It is not possible to create a network with multiple domains.
PTS: 1
Unlike NetWare’s NDS, Active Directory creates a hierarchical structure of resources.
PTS: 1

14.
Unix is most often found with a text-based interface, although graphical user interfaces are available.
ANS: T

PTS: 1

15.
Shortly after its introduction, the Unix software was rewritten in the popular C++ programming language.

ANS: F
16.
ANS: T
17.
ANS: T

PTS: 1
Unix runs on the widest variety of hardware of any network operating system.
PTS: 1
Linux shares many of the same advantages and disadvantages of Unix.
PTS: 1

18.
Linux software cannot support e-mail servers, Web servers, FTP servers, file/print servers, firewalls, proxy servers, and Domain Name System (DNS) servers.
ANS: F
19.
ANS: T
20.
ANS: T
21.
ANS: F
22.
ANS: T

PTS: 1
Mac OS X Server is based on the Unix concept.
PTS: 1
A network operating system needs a host machine from which to operate.
PTS: 1
Network servers only include mainframe computers.
PTS: 1
Many of the higher-power network servers support not one but multiple processors.
PTS: 1

23.
A network server requires at least three connections to the network in the form of a network interface card.
ANS: F
24.
networks.
ANS: T

PTS: 1
When peer-to-peer networks first appeared roughly 30 years ago, they were serverless
PTS: 1

25.
Recently, business and home computer users have been victims of another type of intrusion from unscrupulous outsiders—spyware.
ANS: T
26.
ANS: F
27.

PTS: 1
Wireless sniffers cannot detect how far wireless signals reach.
PTS: 1
Browsers allow users to download and view World Wide Web pages.

ANS: T

PTS: 1

28.
When a software package is installed on a multiuser system, it is not possible for multiple users to execute multiple copies of the single program.
ANS: F

PTS: 1

29.
Every software company may create its own brand of user licenses and may name them something unique.
ANS: T

PTS: 1

MULTIPLE CHOICE
1.
The ____ manages all the other programs (applications) and resources (such as disk drives, memory, and peripheral devices) in a computer.
a.

print server

c.

file server

b.

operating system

d.

user system

ANS: B

PTS: 1

2.
A modern operating system must provide various levels of operating system ____, including directory and file security, memory security, and resource security.
a.

size

c.

security

b.

memory

d.

space

ANS: C

PTS: 1

3.
A(n) ____ sends messages to applications, an interactive user, or a system operator about the status of the current operation.
a.

operating system

c.

hub

b.

router

d.

switch

ANS: A

PTS: 1

4.
Popular operating systems for microcomputers include Mac OS X, ____, Linux, and the various forms of Windows XP/Vista/7.
a.

OS/390

c.

DEC’s VMS

b.

AS/400

d.

Unix

ANS: D

PTS: 1

5.
The ____ server is usually a high-powered workstation that maintains a large file system of data sets, user profiles, and access information about all the network peripherals.
a.

network

c.

print

b.

file

d.

operating system

ANS: A

PTS: 1

6.
A ____ operating system should be capable of supporting the applications and tools necessary to support Internet operations.
a.
print
c.
file
b.

network

d.

ANS: B
7.
systems.

memory

PTS: 1
____ was founded in 1983 and was one of the first developers of network operating

a.

Compaq

c.

Novell

b.

HP

d.

Gateway

ANS: C

PTS: 1

8.
____ is an intelligent system that authenticates users and includes a distributed database of information about every application, user, server, and resource on a network.
a.

NetWare Directory
Services (NDS)

c.

LDAP

b.

Active Directory

d.

X.509

ANS: A

PTS: 1

9.
An interesting feature shared by all versions of NetWare is that the ____ is virtually invisible to the user.
a.

login process

c.

user interface

b.

logout process

d.

loading process

ANS: C
10.
area network.

PTS: 1
The ____ network operating systems were the first to perform redirection on a local

a.

Linux

c.

Windows NT

b.

Unix

d.

Novell

ANS: D
11.

PTS: 1
The first version of NetWare to gain widespread popularity was ____.

a.

Version 1

c.

Version 5

b.

Version 3

d.

Version 6

ANS: B
12.

PTS: 1
One of NetWare Version 3’s main features is the ____.

a.

bindery

c.

X.509

b.

LDAP

d.

iPrint

ANS: A

PTS: 1

13.
The ____ of NetWare version 3 holds information about other services provided by the server to the client, such as printer, modem, and switch/router access information.
a.
iPrint
c.
Remote Manager
b.

iClient

d.

ANS: D
14.

bindery

PTS: 1
NetWare ____ introduced NetWare Directory Services (NDS).

a.

Version 2

c.

Version 4

b.

Version 3

d.

Version 6

ANS: C
15.

PTS: 1
NDS is based on a well-known standard for directory services called ____.

a.

X.300

c.

X.600

b.

X.500

d.

X.700

ANS: B

PTS: 1

16.
On most network operating systems, the client workstation must be loaded with a substantial set of software. With ____, all a user needs on his or her client workstation is a Web browser. a.

NetWare 3

c.

NetWare 5

b.

NetWare 4

d.

NetWare 6

ANS: D

PTS: 1

17.
NetWare ____ server gives any authorized client anywhere on the Internet the ability to print and use storage services.
a.

3

c.

5

b.

4

d.

6

ANS: D

PTS: 1

18.
First released in August 1996, Windows ____ contained a number of significant features that quickly made it a serious competitor in the network operating system market.
a.

2000

c.

Me

b.

NT Version 4

d.

XP

ANS: B

PTS: 1

19.
Windows ____, released in the year 2000, was the next generation of the Windows NT operating system and represented a significant improvement over the earlier versions of NT.
a.

Me

c.

Server 2000

b.

XP

d.

Server 2000N

ANS: C

PTS: 1

20.
Windows Server 2000 incorporated Microsoft’s answer to the highly popular NetWare
NDS directory system: ____.
a.
inode
c.
iPrint
b.

X.509

ANS: D
21.

d.

Active Directory

PTS: 1
Active Directory is built around the ____.

a.

X.500 standard

b.

Lightweight Directory Access Protocol (LDAP)

c.

802.11 protocol

d.

Ethernet standard

ANS: B
22.

PTS: 1
The most recent version of the Windows network operating system is Windows ____.

a.

XP

c.

2003

b.

2000

d.

2008

ANS: D

PTS: 1

23.
____ is a popular operating system that can be found on single-user workstations but primarily functions well on mainframe computers and network servers.
a.

Unix

c.

Windows Me

b.

Linux

d.

Windows 95

ANS: A

PTS: 1

24.
To protect the server from catastrophic disk failure, the disk drives on most network servers support one of the ____ techniques.
a.

Lightweight Directory Access Protocol (LDAP)

b.

IDE

c.

redundant array of independent disks (RAID)

d.

USB

ANS: C
25.

PTS: 1
____ technique is also known as disk mirroring.

a.

RAID-0

c.

RAID-3

b.

RAID-1

d.

RAID-5

ANS: B card. 26.

PTS: 1
A ____ is a server that has no cabinet or box, but resides on a single printed circuit

a.

peer-to-peer server

c.

server blade

b.

server appliance

d.

print server

ANS: C

PTS: 1

27.
____ software is designed to detect and remove viruses that have infected your memory, disks, or operating system.
a.

Antivirus

c.

Uninstall

b.

Remote access

d.

Backup

ANS: A
28.

PTS: 1
____ software is used to block unwanted e-mail and is available at many levels.

a.

Antivirus

c.

Crash protection

b.

Network-monitoring

d.

Anti-spam

ANS: D

PTS: 1

29.
____ software can locate and clean the spyware programs found in a computer’s memory and hard disk drive.
a.

Antispam

c.

Crash protection

b.

Antispyware

d.

Backup

ANS: B

PTS: 1

30.
The primary goal of ____ software is to perform crash stalling, or to try to keep the operating system running long enough to perform a graceful exit.
a.

antivirus

c.

sniffer

b.

network monitoring

d.

crash protection

ANS: D
31.

PTS: 1
____ software incorporates a fairly large number of network support tools.

a.

Network-monitoring

c.

Antispam

b.

Crash protection

d.

Backup

ANS: A

PTS: 1

32.
____ software allows a user to access all of the possible functions of a personal computer workstation from a mobile or remote location.
a.

Network monitoring

c.

Remote access

b.

Sniffer

d.

Antispyware

ANS: C

PTS: 1

33.
____ software works with the user to locate and remove applications that are no longer desired.

a.

Uninstall

c.

Remote access

b.

Backup

d.

Network monitoring

ANS: A

PTS: 1

34.
____ software is the application or set of programs that stores Web pages and allows browsers from anywhere in the world to access those Web pages.
a.

Remote access

c.

Web server

b.

Network monitoring

d.

Antivirus

ANS: C

PTS: 1

35.
Under the terms of the ____ license, the software package may be installed on a single machine, and then only a single user at one time may be using that machine.
a.

interactive user

c.

site

b.

single-user-single-station

d.

network server

ANS: B

PTS: 1

36.
A(n) ____ license is designed for the user who might have a desktop machine at work and a laptop machine for remote sites, or another desktop machine at home.
a.

single-user-single-station

c.

site

b.

interactive user

d.

single-user-multiple-station

ANS: D

PTS: 1

37.
With a system-based or ____ license, there is rarely a software counter controlling the current number of users.
a.

network server

c.

site

b.

interactive user

d.

corporate

ANS: A

PTS: 1

38.
A ____ license allows a software package to be installed on any and all workstations and servers at a given site.
a.

network server

c.

corporate

b.

site

d.

single-user-multiple-station

ANS: B

PTS: 1

39.
A ____ license allows a software package to be installed anywhere within a corporation, even if installation involves multiple sites.
a.

site

c.

corporate

b.

network server

d.

single-user-single-station

ANS: C
40.

PTS: 1
A(n) ____ is a valuable device in the event of a power failure.

a.

media converter

c.

thin client

b.

Blu-Ray DVD

d.

uninterruptible power supply (UPS)

ANS: D

PTS: 1

COMPLETION
1.
A(n) _________________________ is the program initially loaded into computer memory when the computer is turned on.
ANS:
operating system operating system (OS)
OS
OS (operating system)
PTS: 1
2.
Even after an application starts and is being executed, the application makes use of the operating system by making service requests through a defined
___________________________________.
ANS: application program interface (API) application program interface
API
API (application program interface)
PTS: 1
3.
In a(n) ____________________ operating system, multiple programs can be running at the same time.
ANS: multitasking
PTS: 1
4.
A(n) ______________________________ is a large, complex program that can manage the common resources on most local area networks.
ANS:
network operating system (NOS) network operating system
NOS
NOS (network operating system)
PTS: 1
5.
____________________ allows all future print requests to be automatically forwarded to the network printer in an operation that is transparent to both you and the application.
ANS: Redirection

PTS: 1
6.
The NetWare ____________________ in version 3 was a structure (similar to a database) that contains the usernames and passwords of network users and groups of users authorized to log in to that server.
ANS: bindery
PTS: 1
7.
NetWare ____________________ (NDS) is a database that maintains information on and access to every resource on the network, including users, groups of users, printers, data sets, and servers. ANS: Directory Services
PTS: 1
8.
A(n) _________________________ is an object that is further composed of additional objects (examples of which include servers, printers, users, or groups of users).
ANS:
organizational unit (OU) organizational unit
OU
OU (organizational unit)
PTS: 1
9.
____________________ objects are not composed of any objects and are usually entities such as the users, peripherals, servers, printers, queues, and other network resources.
ANS: Leaf
PTS: 1
10.
The NT ____________________ was a container object that contained users, servers, printers, and other network resources.
ANS: domain
PTS: 1
11.
Microsoft’s ____________________ stores information about all the objects and resources in a network and makes this information available to users, network administrators, and application programs.
ANS: Active Directory
PTS: 1

12.
As in Windows NT, the main object in Windows Server 2000 is the
____________________.
ANS: domain
PTS: 1
13.
A(n) ____________________ is the computer that stores software resources such as the network operating system, computer applications, programs, data sets, and databases, and either allows or denies workstations connected to the network access to these resources.
ANS: network server
PTS: 1
14.
_____________________________________________ is a collection of techniques for interfacing multiple hard disk drives to a computer.
ANS:
Redundant array of independent disks (RAID)
Redundant array of independent disks
RAID
RAID (Redundant array of independent disks)
PTS: 1
15.
functions.

A(n) ____________________ is a single unit or box that supports many networking

ANS: server appliance
PTS: 1
16.
A(n) ____________________ may not have any servers but allows communications between workstations, as if the workstations were all equals.
ANS: peer-to-peer network
PTS: 1
17.
____________________ are software programs that operate in the background and support one or more functions to keep the network running at optimal performance.
ANS: Utilities
PTS: 1
18.
____________________, or unsolicited commercial bulk e-mail, has become a major nuisance to corporate users as well as individuals.
ANS: Spam

PTS: 1
19.
____________________ is software that a user unknowingly downloads from the
Internet; and when this software is executed on the user’s machine, it begins spying on the user.
ANS: Spyware
PTS: 1
20.
____________________ software allows network administrators to back up data files currently stored on the network server’s hard disk drive.
ANS: Backup
PTS: 1
21.
____________________ can “listen” to traffic on a network and determine if invalid messages are being transmitted, report network problems such as malfunctioning NICs, and detect traffic congestion problems.
ANS: Sniffers
PTS: 1
22.
____________________ software is designed to scan an IP address or range of IP addresses for any type of security weakness.
ANS: Security assessment
PTS: 1
23.
One of the fastest growing segments of the software market is
____________________ software, the tool set to support Internet-related services.
ANS: Internet
PTS: 1
24.
The ____________________ that accompanies a software product is a legal contract and describes a number of conditions that must be upheld for proper use of the software package.
ANS: licensing agreement
PTS: 1
25.
A(n) ____________________ license, operating system user license, and controlled number of concurrent users license all refer to essentially the same situation.
ANS: interactive user
PTS: 1

ESSAY
1.

What are the functions performed by a network operating system?

ANS:
A network operating system functions can be summarized as follows:
* Manage one or more network servers
- Maintain a file system of data sets, applications, user profiles, network peripherals
- Coordinate all resources and services available
- Process requests from users
- Prompt users for network login, validate accounts, apply restrictions, perform accounting functions
* Manage one or more network printers
* Manage the interconnection between local area networks
* Manage locally connected users
* Manage remotely connected users
* Support system security
* Support client/server functions
* Support Web page development and Web server operations
PTS: 1
2.

How does the NetWare Directory Services (NDS) work?

ANS:
In the NDS, all network resources are considered to be objects, regardless of their actual physical location. NDS is global to the network and is replicated on multiple servers to protect it from failure at a single point. Because NDS is global, users can log in from any location on the network and access any resources for which they have been granted permission. Every user who is allowed to log in to the network is entered into the NDS by the network administrator. Likewise, all network support devices such as printers are also entered into the NDS. For example, if user X wants to use printer Y, the network administrator has to assign the appropriate permissions to allow user X to access printer Y.
These permissions are also entered into the NDS. Every time user X logs on and tries to send a print job to printer Y, the NDS is referenced for the necessary permissions.
The basic idea underlying NDS is that the network administrator must create a hierarchical tree that represents the layout of the organization. This hierarchical structure actually resembles an inverted tree, with the root at the top and the users and network resources—the leaves—at the bottom. This tree could correspond to the physical layout of the organization: for example, workstations 1 through 20 will be on the third floor of an office building, workstations 21 through 40 on the second floor, and workstations 41 through 60 on the first floor. A more powerful and flexible hierarchical tree can be created based on a logical layout. For example, a logical layout could describe the organization in terms of its departmental structure: the engineering department (which could be scattered over floors 1 through 3), the sales department (which could be situated on floors 2, 6, and 7), and marketing (which might be physically located in two different buildings).
PTS: 1
3.

What are the four steps for creating a good and appropriate tree design?

ANS:
Creating a good and appropriate tree design is not a trivial task; however, the following four basic steps will give the network administrator a good start. First, gather the appropriate corporate

documents so that you know about the available hardware and software and the employee departments and divisions. As part of this first step, you should obtain an organizational chart.
Second, design the top section of the tree before you design any lower sections. To design the top section of the tree, you give the top level of the tree the name of the organization object (in most cases, the name of the company) and then create the first layer of organizational units, or container objects.
For example, a division in a company that is composed of multiple departments would be considered an organizational unit. A department is also an organizational unit because it too is further composed of objects, such as employees. If your network is very small, there may not be a need for any organizational units.
Third, you design the bottom section of the tree, which includes the remaining hierarchy of organizational units and leaf objects. Leaf objects are not composed of any objects and are usually entities such as the users, peripherals, servers, printers, queues, and other network resources.
The fourth and final step in creating a tree is to design the security access rights—determine who has rights to the appropriate objects. For example, if you create a new user and place that user in a particular location on the tree, what rights will that user have? What printers and directories will that user be able to access?
PTS: 1
4.

What are some of the features offered by Windows 2003/2008?

ANS:
Although it does not appear to be a major reorganization of the operating system—as Windows 2000 was, when compared to Windows NT—Windows 2003 does offer many new features that network administrators may find useful. Some of these features are:
* Updates to the Active Directory, including a new management tool that unifies all the tasks related to group policy
* Capability to interconnect (cluster) up to eight Windows 2003 servers for better user and application support * New and improved file and print support services, including increased reliability, wider range of supported printers, and remote document sharing
* Support for Internet Protocol version 6 (IPv6)
* Better security features for files, networks, servers, the operating system, and Web-based transactions PTS: 1
5.

What are some of the more common RAID techniques?

ANS:
Some of the more common RAID techniques include:
* RAID-0, in which the data is broken into pieces, and each piece is stored on different disk drives.
This technique is known as striping. There is no redundancy of data in this technique, so if one disk drive fails, some of the data is lost. The advantage of this technique, however, is the speed at which data can be read or written across multiple disks at the same time.
* RAID-1, in which the data is stored on at least two disk drives, in duplicate, to provide a level of redundancy (or fault tolerance), should one disk become corrupted. This technique is also known as disk mirroring.

* RAID-3, in which the data is redundantly stored across multiple disk drives (striping), and errorchecking information concerning the stored data is kept on a separate disk. This error-checking information can be used to detect errors and possibly reconstruct the data should some of it become corrupted. * RAID-5, in which data is broken into pieces (stripes) and stored across three or more disks. Parity information (error-checking code) is stored along with the striped data, not on a separate disk. RAID-5 is the most popular of the RAID techniques.
PTS: 1

Chapter 9: Introduction to Metropolitan Area Networks and Wide Area Networks
TRUE/FALSE
1.
ANS: T
2.
ANS: T

Wide area networks share a few characteristics with local area networks.
PTS: 1
Wide area networks now carry both data and voice.
PTS: 1

3.
Many of the same technologies and communications protocols found in local area networks are used to create metropolitan area networks.
ANS: T
4.
ANS: F
5.
ANS: T
6.
ANS: F
7.
ANS: T
8.
ANS: F
9.
ANS: T

PTS: 1
LANs cover much greater distances than MANs do.
PTS: 1
Some MAN topologies are based on a ring.
PTS: 1
Most MANs are supported by Ethernet ring technology.
PTS: 1
SONET was designed to support multiple streams of voice channels.
PTS: 1
Local area network Ethernet allows users to set their own data transfer rates.
PTS: 1
A wide area network would not exist without a sub-network.
PTS: 1

10.
A wide area network’s sub-network, or cloud, may be categorized by the way it transfers information from one end of the sub-network to the other.
ANS: T
11.
ANS: T
12.
ANS: F
13.
ANS: F
14.
ANS: T

PTS: 1
A virtual circuit breaks a large amount of data into n packets.
PTS: 1
The path in a circuit-switched network exists only in the software.
PTS: 1
Broadcast networks are as common as circuit-switched and packet-switched networks.
PTS: 1
Circuit-switched networks were designed primarily for voice signals.
PTS: 1

15.
The sub-network of a wide area network is the logical infrastructure and thus consists of nodes and various types of interconnecting media.
ANS: F

PTS: 1

16.
To provide a reliable service, the network requires that a logical connection be established between the two endpoints.
ANS: T
17.
ANS: F

PTS: 1
A common example of a connection-oriented network application is DNS.
PTS: 1

18.
The underlying sub-network of a connectionless application cannot be a circuitswitched network.
ANS: F

PTS: 1

19.
A wide area network’s underlying sub-network consists of multiple nodes, each with multiple possible connections to other nodes within the sub-network.
ANS: T
20.
ANS: T

PTS: 1
You can assign many meanings to the weights in a weighted network graph.
PTS: 1

21.
Most wide area networks use some form of Dijkstra’s algorithm to determine a leastcost route through a network.
ANS: T

PTS: 1

22.
Compared to Dijkstra’s least-cost routing algorithm, the flooding technique seems more complex.
ANS: F

PTS: 1

23.
The major disadvantage of flooding is the large number of copied packets distributed throughout the network.
ANS: T

PTS: 1

24.
One disadvantage of distributed routing is related to the problems that arise if the routing tables need to be updated.
ANS: T

PTS: 1

25.
When all the routing information is in one place, it is difficult to make updates to the routing information.
ANS: F

PTS: 1

26.
The first routing algorithm used within the Internet was called a distance vector routing algorithm.
ANS: T
27.
ANS: F

PTS: 1
Any network is as strong as its strongest link.
PTS: 1

28.
Some congestion control methods are based on simple techniques such as the flow control methods.
ANS: T

PTS: 1

29.
CSMA/CD is the only network technology that successfully supports connection admission control and quality of service.
ANS: F
30.
ANS: F
31.
ANS: F

PTS: 1
CSMA/CA is the most popular LAN protocol.
PTS: 1
Circuit-switched networks will someday replace packet-switched networks.
PTS: 1

MULTIPLE CHOICE
1.
one building.

A ____ area network is typically confined to a single building or a couple floors within

a.

personal

c.

metropolitan

b.

local

d.

wide

ANS: B
2.

PTS: 1
A network that expands beyond a metropolitan area is a ____ area network.

a.

personal

c.

metropolitan

b.

local

d.

wide

ANS: D
3.

PTS: 1
____ area networks can cover large geographic distances, including the entire Earth.

a.

Personal

c.

Wide

b.

Local

d.

Universal

ANS: C

PTS: 1

4.
MANs are almost exclusively ____ networks, and thus capable of supporting data rates into the tens of millions and hundreds of millions of bits per second.
a.

fiber-optic

c.

twisted-paired

b.

copper-wired

d.

coaxial-cabled

ANS: A
5.
throughput.

PTS: 1
____ are advertised as networks with very low error rates and extremely high

a.

PANs

c.

GANs

b.

UANs

d.

MANs

ANS: D

PTS: 1

6.
A feature that is fairly common in ____ is the ability of a user to dynamically allocate more bandwidth on demand.
a.

PANs

c.

MANs

b.

LANs

d.

WANs

ANS: C
7.
or Ethernet.

PTS: 1
Almost all MANs are based on one of two basic forms of supporting technology: ____

a.

SONET

c.

GALNET

b.

SOHO

d.

SWNET

ANS: A
8.

PTS: 1
The SONET network topology is a ____.

a.

star

c.

bus

b.

ring

d.

star-bus

ANS: B
9.

PTS: 1
SONET rings typically have a failover time of ____ milliseconds.

a.

20

c.

40

b.

30

d.

50

ANS: D

PTS: 1

10.
A ____ profile describes various characteristics about the connection, such as basic data transfer rates, basic burst rates, excess data transfer rates, and excess burst rates.
a.

bandwidth

c.

client

b.

server

d.

router

ANS: A

PTS: 1

11.
A local area network works as a ____ network in that clusters of workstations are connected to a central point (hub or switch) through which workstations can transmit messages to one another. a.

star-based

c.

ring-based

b.

bus-based

d.

star-ring-based

ANS: B

PTS: 1

12.
A wide area network connects its workstations through the use of a ____ design and requires routing to transfer data across the network.
a.

bus

c.

mesh

b.

star

d.

ring

ANS: C
13.
neighbors.

PTS: 1
A network that is connected in a ____ is one in which neighbors are connected only to

a.

star

c.

bus

b.

mesh

d.

star-bus

ANS: B

PTS: 1

14.
All wide area networks are collections of at least two basic types of equipment: a station and a ____.
a.

link

c.

workstation

b.

server

d.

node

ANS: D

PTS: 1

15.
The type and number of interconnections between nodes and the way network data is passed from node to node are the responsibility of the ____.
a.
sub-network
c.
server
b.

station

d.

ANS: A
16.

client

PTS: 1
The three basic types of subnetworks are ____, packet-switched, and broadcast.

a.

multicast

c.

circuit-switched

b.

protocol-switched

d.

unicast

ANS: C

PTS: 1

17.
The ____-switched network is most often found in networks designed to transfer computer data (such as the Internet).
a.

circuit

c.

protocol

b.

packet

d.

port

ANS: B

PTS: 1

18.
To distinguish between a piece of data processed at the data link layer and a piece of data processed at the network layer, the term “____” is used at the data link layer, and the term
“packet” is used at the network layer.
a.

load

c.

frame

b.

product

d.

payload

ANS: C
19.

PTS: 1
The two types of packet-switched networks are the datagram and the ____.

a.

static circuit

c.

standard circuit

b.

fixed circuit

d.

virtual circuit

ANS: D

PTS: 1

20.
When a node on a wide area network ____ network transmits its data, the data is received by all the other nodes.
a.

broadcast

c.

circuit-switched

b.

packet-switched

d.

datagram packet-switched

ANS: A

PTS: 1

21.
____ and virtual circuit networks require path setup time and cannot dynamically reroute packets should a network problem occur.
a.

Broadcast

c.

Circuit-switched

b.

Wireless

d.

Datagram

ANS: C

PTS: 1

a.

22.
A ____ network is the only network that offers a dedicated path. packet-switched c. virtual circuit

b.

broadcast

ANS: D

d.

circuit-switched

PTS: 1

23.
A ____ network application provides some guarantee that information traveling through the network will be delivered to the intended receiver in the same order in which it was transmitted. a.

connectionless

c.

virtual circuit

b.

connection-oriented

d.

packet-switched

ANS: B
24.

PTS: 1
A ____ application does not guarantee the delivery of any information or data.

a.

connectionless

c.

virtual circuit

b.

connection-oriented

d.

packet-switched

ANS: A

PTS: 1

25.
____ applications do not negotiate a connection, and the transfer of data is rarely, if ever, acknowledged.
a.

FTP

c.

Connection-oriented

b.

Connectionless

d.

Reliable service

ANS: B
26.
algorithm.

PTS: 1
A classic algorithm that calculates a least-cost path through a network is ____

a.

Dijkstra’s maximum-cost

c.

Turing’s longest-path

b.

Dijkstra’s longest-path

d.

Dijkstra’s least-cost

ANS: D

copied.

27.

PTS: 1
A network limit, called the ____, can be placed on how many times any packet is

a.

hop limit

c.

time to live

b.

hop count

d.

time to hop

ANS: A

PTS: 1

28.
Each time a packet is copied, a counter associated with the packet increases by one.
This counter is called the ____.
a.

hop limit

c.

TTL count

b.

time to live

d.

hop count

ANS: D

PTS: 1

a.

29.
____ is advantageous when a copy of a packet needs to get to all nodes.
Flooding
c.
Dijkstra’s shortest-path

b.

Dijkstra’s least-cost

ANS: A
30.

d.

Dijkstra’s maximum-cost

PTS: 1
____ routing involves storing all the routing information at one central location.

a.

Distributed

c.

Remote

b.

Centralized

d.

Fixed

ANS: B

PTS: 1

31.
One of the primary advantages of ____ routing is the fact that no single node is responsible for maintaining all routing information.
a.

centralized

c.

distributed

b.

focalized

d.

local

ANS: C
32.

PTS: 1
____ and distributed routing are methods for sending routing information.

a.

Distributed

c.

Fixed

b.

Adaptive

d.

Centralized

ANS: D
33.

PTS: 1
When routing tables adapt to network changes, the routing system is called ____.

a.

fixed

c.

adaptive

b.

local

d.

static

ANS: C

PTS: 1

34.
With ____ routing, routing tables are created once, typically when the network is installed, and then never updated again.
a.

fixed

c.

changing

b.

adaptive

d.

modifying

ANS: A

PTS: 1

35.
When a network or a part of a network becomes so saturated with data packets that packet transfer is noticeably impeded, ____ occurs.
a.

network flowing

c.

frame control

b.

packet control

d.

network congestion

ANS: D

PTS: 1

36.
When an application is simply observing its own throughput and not relying on any special types of signals coming from the network, this is called ____ congestion control.
a.
explicit
c.
forward explicit
b.

implicit

ANS: B

d.

backward explicit

PTS: 1

37.
With ____, when a frame relay router experiences congestion, it sends a congestion signal forward to the destination station, which in turn tells the originating station to slow down the transfer of data.
a.

forward explicit congestion notification (FECN)

b.

backward explicit congestion notification (BECN)

c.

implicit congestion control

d.

remote congestion control

ANS: A

PTS: 1

38.
In ____, before one node sends a series of n packets to another node, the sending node inquires in advance whether the receiving node has enough buffer space for the n packets.
a.

explicit congestion control c.

connection admission control

b.

implicit congestion control d.

buffer preallocation

ANS: D

PTS: 1

39.
____ avoids congestion by requiring users to negotiate with the network regarding how much traffic they will be sending, or what resources the network must provide to satisfy the user’s needs before the user sends any data.
a.

Explicit congestion control c.

Connection admission control

b.

Implicit congestion control d.

Buffer preallocation

ANS: C

PTS: 1

40.
A ____ is a legally binding, written document, that can include service parameters offered in the service, various types of service/support options, incentives if the service levels are exceeded, and penalties if service levels are not met.
a.

connection admission control c.

software license agreement

b.

service level agreement

d.

congestion control

ANS: B

COMPLETION

PTS: 1

1.
A network that expands into a metropolitan area and exhibits high data rates, high reliability, and low data loss is called a(n) ___________________________________.
ANS:
metropolitan area network (MAN) metropolitan area network
MAN
MAN (metropolitan area network)
PTS: 1
2.

The ability to reroute in the event of a failure is called ____________________.

ANS: failover
PTS: 1
3.

The speed at which a failover is performed is the ____________________.

ANS: failover time
PTS: 1
4.
____________________ is a synchronous time division multiplexing technique that is capable of sending data at hundreds of millions of bits per second.
ANS: SONET
PTS: 1
5.
____________________ is a data transfer service that can connect your business to another business (or businesses) using a standard Ethernet connection.
ANS: Metro Ethernet
PTS: 1
6.
A company that has a connection with Metro Ethernet can create a(n)
____________________ for that connection.
ANS: bandwidth profile
PTS: 1
7.
A(n) ____________________ is a large surge of data that’s transmitted for a short period of time.
ANS: burst
PTS: 1

8.
A(n) _________________________ is a collection of computers and computer-related equipment interconnected to perform a given function or functions and typically using local and longdistance telecommunications systems.
ANS:
wide area network (WAN) wide area network
WAN
WAN (wide area network)
PTS: 1
9.
A(n) ____________________ is a device that a user interacts with to access a network, and it contains the software application that allows someone to use the network for a particular purpose.
ANS: station
PTS: 1
10.
A(n) ____________________ is a device that allows one or more stations to access the physical network and is a transfer point for passing information through the network.
ANS: node
PTS: 1
11.
A(n) ____________________ is a collection of nodes and interconnecting telecommunications links.
ANS: sub-network, or cloud
PTS: 1
12.
A(n) ____________________ network is a sub-network in which a dedicated circuit is established between sender and receiver, and all data passes over this circuit.
ANS: circuit-switched
PTS: 1
13.
In a(n) ____________________ network, all data messages are transmitted using fixed-sized packages, called packets, and no unique, dedicated physical path is established to transmit the data packets across the subnetwork.
ANS: packet-switched
PTS: 1
14.
In a(n) ____________________ packet-switched network, each data packet can follow its own, possibly unique, course through the sub-network.

ANS: datagram
PTS: 1
15.
In a(n) ____________________ packet-switched network, all packets that belong to a logical connection can follow the same path through the network.
ANS: virtual circuit
PTS: 1
16.
A(n) ____________________ network application provides some guarantee that information traveling through the network will not be lost.
ANS: connection-oriented
PTS: 1 service. 17.

A connection-oriented network application provides what is called a(n) ___________

ANS: reliable
PTS: 1
18.
A(n) ____________________ network application does not require a logical connection to be made before the transfer of data.
ANS: connectionless
PTS: 1
19.
In a network graph, the edge between each pair of nodes can be assigned a weight or associated cost to form a structure called a(n) _________________________.
ANS: weighted network graph
PTS: 1
20.
____________________ states that each node takes the incoming packet and retransmits it onto every outgoing link.
ANS: Flooding
PTS: 1
21.
____________________ routing is a technique that uses a routing algorithm to generate routing information and dictates that this information be stored at distributed locations within the network.
ANS: Distributed

PTS: 1
22.
____________________ routing is a dynamic technique in which routing tables react to network fluctuations, such as congestion and node/link failure.
ANS: Adaptive
PTS: 1
23.
______________________________ protocol is a link state algorithm and is still used today by many Internet routers.
ANS:
Open Shortest Path First (OSPF)
Open Shortest Path First
OSPF
OSPF (Open Shortest Path First)
PTS: 1
24.
When the network signals the transmitting station to slow down, this is called
_________________________.
ANS: explicit congestion control
PTS: 1
25.
With _____________________________________________, the frame relay router experiencing congestion sends a signal back to the originating station, which then slows down its transmission. ANS: backward explicit congestion notification (BECN) backward explicit congestion notification
BECN
BECN (backward explicit congestion notification)
PTS: 1

ESSAY
1.

Briefly explain the most important aspects of a Metro Ethernet.

ANS:
Ethernet MANs have given rise to a newer service whose popularity has grown in the last few years:
Metro Ethernet. Metro Ethernet is a data transfer service that can connect your business to another business (or businesses) using a standard Ethernet connection. With Metro Ethernet, you may connect your company directly to another company using a point-to-point connection, or, for example, to two other companies using two point-to-point connections. Alternatively, you may connect your company to multiple companies as though they were all part of a large local area network. The former connection is the same as having a private connection between two points. A common example of this type of Metro Ethernet connection is found when a company is connected to an Internet service

provider. All the traffic on this connection is between only two locations. The latter connection is an example of a multipoint-to-multipoint connection. Here, any company can talk to one or more (or all) connected companies. Thus, a company needs to send out only one packet to ensure that multiple companies receive this data.
PTS: 1
2.

Provide and explain an example of a circuit-switched network.

ANS:
One of the best examples of a circuit-switched network is the dial-up telephone system. When someone places a call on a dial-up telephone network, a circuit, or path, is established between the person placing the call and the recipient of the call. This physical circuit is unique, or dedicated, to this one call and exists for the duration of the call. The information (the telephone conversation) follows this dedicated path from node to node within the network. A wide area network in which information follows a dedicated path from node to node within the network is a circuit-switched wide area network. When a telephone call is placed over a circuit-switched network, the network needs time to establish the circuit and to tear down the circuit. But once the circuit is established, all subsequent data travels quickly from node to node. A circuit-switched network has two key disadvantages. First, each circuit is dedicated to only one connection. Second, when the circuit is used to transfer data (as opposed to voice), it is probably not being utilized fully, because computer data transfer is often sporadic.
PTS: 1
3.

How does a virtual circuit packet-switched network work?

ANS:
In a virtual circuit packet-switched network, all packets that belong to a logical connection can follow the same path through the network. For example, one station may want to transfer a large amount of data, such as the entire electronic contents of a book, across the network to another station. To accomplish this, a virtual circuit breaks the large amount of data into n packets and determines an optimal temporary path through the network. Each router along the path is then informed that it will be participating in a particular virtual circuit. When the data arrives with the address of that particular virtual circuit, the router simply sends the data out the router connection that is associated with that virtual circuit. When the data transfer is complete, the temporary path is dissolved (that is, each router tosses that virtual circuit information). This type of packet-switched network is called a virtual circuit because the path followed by the packets acts like a circuit but is not an actual, physical circuit like a telephone circuit.
PTS: 1
4.

How is routing through a wide area network accomplished?

ANS:
Consider the Internet as an example: It is a massive collection of networks, routers, and communications lines (various types of telephone lines). When a data packet enters a router, the router examines the IP address encapsulated in the network layer of the packet and determines where the packet should go next. When there are multiple routes through a network such as the Internet, how is any one particular route selected? Although routing on the Internet is fairly complex, it is possible to examine the basic routing techniques that all types of wide area networks employ. But keep in mind

that a wide area network does not use only one form of routing. The routing algorithms used within the
Internet, for example, are actually combinations of several types of basic routing techniques.
To begin to understand the often complex issue of routing, it is helpful to think of the sub-network as a graph consisting of nodes (computers, routers, or telephone switches) and edges (the communications links between the nodes).
PTS: 1
5.

What are the problems associated with network congestion?

ANS:
Networks experience congestion for many reasons. A network failure—either failure on a communications link between nodes, or the failure of the node itself—may lead to network congestion.
If the network cannot quickly detect the point of failure and dynamically route around this point, it may experience a wide range of congestion problems, from a small slowdown on an individual link to total network collapse. Even if the network were to begin the rerouting process, it might still experience congestion because one less network path would be available. But communications link and node failures are not the only causes of congestion. Insufficient buffer space at a node in a subnetwork can also cause network congestion. It is not uncommon to have hundreds or even millions of packets arriving at a network node each second. If the node cannot process the packets quickly enough, incoming packets will begin to accumulate in a buffer space. When packets sit in a buffer for an appreciable amount of time, network throughput begins to suffer. If adaptive routing is employed, this congestion can be recognized, and updated routing tables can be sent to the appropriate nodes (or to a central routing facility). But changing routing tables to deflect congestion might provide only a temporary fix, if any fix at all. What is needed is a more permanent solution. Two possible more permanent solutions would be increasing the speed of the node processor responsible for processing the incoming data packets and increasing the amount of buffer space in the node. Unfortunately, both of these solutions may take a large amount of time and money to implement. Perhaps less costly alternatives are possible.
What happens if the buffer space is completely full and a node cannot accept any additional packets?
In many systems, packets that arrive after the buffer space is full are discarded. Although this is not a very elegant solution, it momentarily solves the problem of too many packets. Unfortunately, this is like bad medicine— it treats the symptoms, but not the disease. What is needed is a solution that reacts quickly to network congestion and addresses the real problem—too many packets.
PTS: 1

Chapter 10: The Internet
TRUE/FALSE
1.
Current estimates suggest that there are more than 450 million hosts (computer sites that store and deliver Web pages) connected to the Internet.
ANS: T
2.

PTS: 1
IP is a connection-oriented protocol.

ANS: F
3.
ANS: F

PTS: 1
Currently, almost all networks involved in the Internet use IP version 6.
PTS: 1

4.
The IP datagram fields Identification, Flags, and Fragment Offset are used to fragment a datagram into smaller parts.
ANS: T
5.
ANS: T
6.
ANS: F

PTS: 1
The Time to Live field indicates how long a particular datagram is allowed to live.
PTS: 1
A 16-bit address uniquely defines a connection to the Internet.
PTS: 1

7.
When the user wants to send an e-mail message, the e-mail program takes the e-mail message and passes it to the transport layer of the software.
ANS: T
8.
ANS: F
9.
ANS: T

PTS: 1
The Window field of the TCP header cannot be set to zero.
PTS: 1
Like its counterpart IP, TCP is a fairly streamlined protocol.
PTS: 1

10.
IP is the protocol used by most networks and network applications to create an errorfree, end-to-end network connection.
ANS: F
11.
Checksum.
ANS: T
12.
ANS: T
13.
ANS: T
14.

PTS: 1
The UDP header contains only four fields—Source Port, Destination Port, Length, and
PTS: 1
Every device that has a connection to the Internet is assigned an IP address.
PTS: 1
Home and small business local area networks often use NAT to conserve IP addresses.
PTS: 1
Using a Web browser, you can download and view Web pages on a personal computer.

ANS: T
15.
ANS: F

PTS: 1
The Hypertext Transfer Protocol, or HTTP, is a transport layer protocol.
PTS: 1

16.
Every object on the Internet has a unique English-based address called its Uniform
Resource Locator (URL).
ANS: T
17.
ANS: F
18.
ANS: F

PTS: 1
The Internet recognizes URLs directly.
PTS: 1
All Uniform Resource Locators consist of six parts.
PTS: 1

19.
To make IP addresses a little easier for human beings to understand, the 32-bit binary addresses are represented by dotted decimal notation.
ANS: T
20.
ANS: F
21.
ANS: T
22.
ANS: F
23.
closing tag.
ANS: T

PTS: 1
There are six basic forms of a classful IP address: Class A, B, C, D, E, and F.
PTS: 1
IP multicasting suffers from a lack of security.
PTS: 1
Standard Generalized Markup Language (SGML) is a markup language.
PTS: 1
Most HTML tags consist of an opening tag, followed by one or more attributes, and a
PTS: 1

24.
HTML pages are simple, static text documents that browsers read, interpret, and display on the screen.
ANS: T

PTS: 1

25.
POP3 is not useful if you do not have a permanent connection to a network and must dial in using a temporary Internet connection.
ANS: F

PTS: 1

26.
Internet.

The File Transfer Protocol, or FTP, was one of the first services offered on the

ANS: T
27.

PTS: 1
H.323 was originally designed for TCP/IP networks.

ANS: F
28.

PTS: 1
Types of listserv software include mailserv, majordomo, and almanac.

ANS: T
29.
applications.

PTS: 1
Intranets use essentially the same hardware and software that is used by other network

ANS: T
30.

PTS: 1
The Internet is a static entity.

ANS: F

PTS: 1

MULTIPLE CHOICE
1.
During the late 1960s, a branch of the U.S. government titled the ____ created one of the country’s first wide area packet-switched networks.
a.

Department of Defense

b.

IEEE

c.

Advanced Research Projects Agency (ARPA)

d.

IETF

ANS: C

PTS: 1

2.
In 1983, the Department of Defense broke the ARPANET into two similar networks: the original ARPANET and ____.
a.

MILNET

c.

CampusNET

b.

NSFnet

d.

DoDNET

ANS: A

PTS: 1

3.
The National Science Foundation funded the creation of a new high-speed, crosscountry network backbone called the ____.
a.

MILNET

c.

CampusNET

b.

NSFnet

d.

DoDNET

ANS: B

PTS: 1

4.
The ____ is the main telecommunications line through the network, connecting the major router sites across the country.

a.

star topology

c.

mid-level network

b.

ARPANET

d.

backbone

ANS: D
5.

PTS: 1
To transfer Web pages, the Internet uses the ____.

a.

Telnet

c.

e-commerce

b.

Hypertext Transfer
Protocol (HTTP)

d.

Network Address Translation (NAT)

ANS: B
6.

PTS: 1
____ are used to select unique documents from anywhere in the world.

a.

Uniform Resource
Locators (URLs)

c.

Dynamic Host Configuration Protocol

b.

Domain Name Systems
(DNSs)

d.

XMLs

ANS: A

PTS: 1

7.
The protocol that resides at the ____ layer in the TCP/IP protocol suite is called
Internet Protocol (IP).
a.

application

c.

network

b.

transport

d.

network access

ANS: C

PTS: 1

8.
The ____ field of an IP datagram contains the version number of IP being used, just in case a new version becomes available.
a.

Service Type

c.

Protocol

b.

Time to Live

d.

Version

ANS: D

PTS: 1

9.
The IP datagram ____ field enables the network to discard a datagram that has been traveling the Internet for too long.
a.

Time to Live

c.

Total Length

b.

Service Type

d.

IP Options

ANS: A

PTS: 1

10.
The TCP header ____ field contains a 32-bit value that counts bytes and indicates a packet’s data position within the connection.
a.

Source Port

c.

Sequence Number

b.

Padding

d.

Window

ANS: C

PTS: 1

11.
____ is a no-frills transport protocol that does not establish connections, does not attempt to keep data packets in sequence, and does not watch for datagrams that have existed for too long. a.
Transport Control Protocol (TCP)
b.

User Datagram Protocol (UDP)

c.

Internet Control Message Protocol (ICMP)

d.

Network Address Translation (NAT)

ANS: B

PTS: 1

12.
____ takes an IP address in an IP datagram and translates it into the appropriate medium access control layer address for delivery on a local area network.
a.

Transport Control
Protocol (TCP)

c.

Network Address Translation (NAT)

b.

User Datagram Protocol
(UDP)

d.

Address Resolution Protocol (ARP)

ANS: D address. 13.

PTS: 1
____ lets a router represent an entire local area network to the Internet as a single IP

a.

ICMP

c.

ARP

b.

NAT

d.

UDP

ANS: B

PTS: 1

14.
A ____ is a data network connection that makes use of the public telecommunications infrastructure but maintains privacy through the use of a tunneling protocol and security procedures.
a.

NAT network

c.

DHCP

b.

TCP network

d.

virtual private network (VPN)

ANS: D
15.

PTS: 1
The Point-to-Point Tunneling Protocol (PPTP) is an extension of the Internet’s ____.

a.

Internet Protocol (IP)

c.

Point-to-Point Protocol (PPP)

b.

Transport Control
Protocol (TCP)

d.

Address Resolution Protocol (ARP)

ANS: C

PTS: 1

16.
____ is a set of protocols developed by the Internet Engineering Task Force to support the secure exchange of data packets at the IP layer.
a.

IPsec

c.

PPP

b.

PPTP

d.

SLIP

ANS: A

PTS: 1

17.
Internet.
a.
ARP
b.

The Web server software accepts ____ requests from Web browsers connected to the
c.
d.

DHCP

ANS: D

NAT
HTTP

PTS: 1

18.
A(n) ____ uniquely identifies files, Web pages, images, or any other types of electronic documents that reside on the Internet.
a.

File Transfer Protocol
(FTP)

c.

Uniform Resource Locator (URL)

b.

Internet Protocol (IP)

d.

Domain Name Service (DNS)

ANS: C
19.

PTS: 1
The ____ is a large, distributed database of Internet addresses and domain names.

a.

Uniform Resource
Locator (URL)

c.

Hypertext Transfer Protocol (HTTP)

b.

Domain Name System
(DNS)

d.

Hypertext Markup Language (HTML)

ANS: B

PTS: 1

20.
____ is the capability of a network server to transmit a data stream to more than one host at a time.
a.

IP multicasting

c.

TCP broadcasting

b.

TCP unicasting

d.

ICMP multicasting

ANS: A
21.
browser.

PTS: 1
____ is a set of codes inserted into a document that is intended for display on a Web

a.

Domain Name Service
(DNS)

c.

Uniform Resource Locator (URL)

b.

Hypertext Markup
Language (HTML)

d.

Hypertext Transfer Protocol (HTTP)

ANS: B

PTS: 1

22.
____ is a collection of newer markup tags and techniques that can be used to create more flexible and more powerful Web pages.
a.

Dynamic HTML
(DHTML)

c.

Hypertext Transfer Protocol (HTTP)

b.

Address Resolution
Protocol (ARP)

d.

Uniform Resource Locator (URL)

ANS: A

PTS: 1

23. office. a.
FTP
b.

____ is the computerized version of writing a letter and mailing it at the local post
c.
d.

e-business

ANS: D
24.

e-commerce
Electronic mail

PTS: 1
An e-mail program creates a(n) ____ document and attaches it to the e-mail message.

a.

Multipurpose Internet Mail Extensions (MIME)

b.

Address Resolution Message (ARM)

c.

Transport Control Protocol (TCP)

d.

Internet Protocol (IP)

ANS: A

PTS: 1

25.
The ____ is an Internet protocol for sending and receiving e-mail and is used to perform the transfer.
a.

Address Resolution
Protocol (ARP)

c.

File Transfer Protocol (FTP)

b.

Simple Mail Transfer
Protocol (SMTP)

d.

Transport Control Protocol (TCP)

ANS: B

PTS: 1

26.
____ is a client/server protocol in which e-mail is received and held for you at your
Internet server.
a.

Hypertext Transfer Protocol (HTTP)

b.

File Transfer Protocol (FTP)

c.

Domain Name Service (DNS)

d.

Internet Message Access Protocol (IMAP)

ANS: D

PTS: 1

27.
The primary functions of ____ are to allow a user to download a file from a remote site to the user’s computer and to upload a file from the user’s computer to a remote site.
a.

Hypertext Transfer Protocol (HTTP)

b.

Domain Name Service (DNS)

c.

File Transfer Protocol (FTP)

d.

Internet Message Access Protocol (IMAP)

ANS: C

PTS: 1

28.
____ is a terminal emulation program for TCP/IP networks, such as the Internet, that allows users to log in to a remote computer.
a.

Remote login

c.

DNS

b.

ARP

d.

ANS: A

FTP

PTS: 1

29.
The practice of making telephone calls over the Internet has had a number of different names, including packet voice, voice over packet, voice over the Internet, Internet telephony, and
____.
a.

HTML

c.

Voice over IP (VoIP)

b.

SMTP

d.

XHTML

ANS: C

PTS: 1

30.
A company can use IP for transmission of data within its own network, but use traditional telephone lines outside the company network. Many people are now beginning to call such systems ____.
a.

private VoIP

c.

remote VoIP

b.

public VoIP

d.

distributed VoIP

ANS: A

PTS: 1

31.
____ is actually a set of protocols named packet-based multimedia protocols, and it was designed for a wide range of applications (audio and video).
a.

H.121

c.

H.256

b.

H.232

d.

H.323

ANS: D
32.
addresses.

PTS: 1
____ is a protocol that converts telephone numbers to fully qualified domain name

a.

H.323

c.

SIP

b.

ENUM

d.

UDP

ANS: B

PTS: 1

33.
____ involves the continuous download of a compressed audio or video file, which can then be heard or viewed on the user’s workstation.
a.

Streaming audio and video c.

File Transfer Protocol (FTP)

b.

Voice over IP

d.

XML

ANS: A

PTS: 1

34.
____ is a common application layer protocols that servers and the Internet use to deliver streaming audio and video data to a user’s browser.
a.

Secure Shell (SSH)

c.

Real-Time Protocol (RTP)

b.

Transport Control
Protocol (TCP)

d.

Voice over IP (VoIP)

ANS: C
35.

PTS: 1
Real-Time Streaming Protocol (RTSP) is a(n) ____ layer protocol.

a.

physical

c.

transport

b.

network

d.

application

ANS: D
36.

PTS: 1
____ is the electronic selling and buying of merchandise using the Web.

a.

VoIP

c.

E-mail

b.

E-retailing

d.

IM

ANS: B

PTS: 1

37.
____ is the gathering and use of the browsing habits of potential and current customers, which is important data for many companies.
a.

Micro-marketing

c.

VoIP

b.

E-retailing

d.

EDI

ANS: A
38.
workstation.

PTS: 1
A ____ is data created by a Web server that is stored on the hard drive of a user’s

a.

javascript

c.

script

b.

cookie

d.

certificate

ANS: B

PTS: 1

39.
One of the biggest changes to affect the Internet will be the adoption of a new version of the Internet Protocol, version ____.
a.

IPv3

c.

IPv5

b.

IPv4

d.

IPv6

ANS: D

PTS: 1

40.
There is a plan to implement a newer, very high-speed network that will cover the
United States, interconnecting universities and research centers at transmission rates up to a gigabit per second (1000 Mbps). The new high-speed network is called ____.
a.

IPv6

c.

Internet2

b.

FastEthernet

d.

Internet6

ANS: C

COMPLETION

PTS: 1

1.
During the late 1960s, ARPA created one of the country’s first wide area packetswitched networks, the ____________________.
ANS: ARPANET
PTS: 1
2.
The ____________________ provides a connectionless data transfer service over heterogeneous networks by passing and routing IP datagrams.
ANS:
Internet Protocol (IP)
Internet Protocol
IP
PTS: 1
3.

IP ____________________ is essentially another name for a data packet.

ANS: datagram
PTS: 1
4.
The primary function of ___________________________________ is to turn an unreliable network into a reliable network that is free from lost and duplicate packets.
ANS:
Transmission Control Protocol (TCP)
Transmission Control Protocol
TCP
PTS: 1
5.
A(n) ____________________ is a precise identification of a particular application on a particular device.
ANS: socket
PTS: 1
6.
The TCP header ____________________ field contains a sliding window value that provides flow control between the two endpoints.
ANS: Window
PTS: 1
7.
________________________________________ is a technique that enables a router to switch data quickly from one path onto another path.
ANS:
Multiprotocol Label Switching (MPLS)

Multiprotocol Label Switching
MPLS
PTS: 1
8.
The ________________________________________, which is used by routers and nodes, performs error reporting for the Internet Protocol.
ANS:
Internet Control Message Protocol (ICMP)
Internet Control Message Protocol
ICMP
PTS: 1
9.
The most popular protocol that handles dynamic assignment of IP addresses is
________________________________________.
ANS:
Dynamic Host Configuration Protocol (DHCP)
Dynamic Host Configuration Protocol
DHCP
PTS: 1
10.
A(n) ____________________ is the command set that allows an organization to create secure connections using public resources such as the Internet.
ANS: tunneling protocol
PTS: 1
11.
The ____________________ is a vast collection of electronic documents that are located on many different Web servers and contain text and images that can be accessed by simply clicking links within a browser’s Web page.
ANS:
World Wide Web (WWW)
World Wide Web
WWW
PTS: 1
12.
The ____________________ portion of the URL specifies a particular server at a particular site that contains the requested item.
ANS: domain name
PTS: 1
13.
The basic idea behind ____________________ is to take the host ID portion of an IP address and further divide it into a subnet ID and a host ID.

ANS: subnet masking
PTS: 1
14.
______________________________ allow a Web page author to incorporate multiple styles (fonts, styles, colors, and so on) in an individual HTML page.
ANS:
Cascading style sheets (CSS)
Cascading style sheets
CSS
PTS: 1
15.
___________________________________ is a subset of SGML and is a specification for how to create a document—the specification covers both the definition of the document and the contents of the document
ANS:
eXtensible Markup Language (XML) eXtensible Markup Language
XML
PTS: 1
16.
_____________________________________________ combines HTML, dynamic
HTML, and XML into one standard and should eventually replace HTML.
ANS:
eXtensible Hypertext Markup Language (XHTML) eXtensible Hypertext Markup Language
XHTML
PTS: 1
17.
________________________________________ is the software that allows the user to save e-mail messages in a server mailbox and download them when desired from the server.
ANS:
Post Office Protocol version 3 (POP3)
Post Office Protocol version 3
POP3
PTS: 1
18.
The ____________________ can perform the digitization, compression, and encapsulation required, and it controls the setup of VoIP calls between the calling device and the called device. ANS: VoIP gateway

PTS: 1
19.
___________________________________ was introduced in 1998 by the Internet
Engineering Task Force specifically for supporting the transfer of voice over the Internet.
ANS:
Session Initiation Protocol (SIP)
Session Initiation Protocol
SIP
PTS: 1
20.
A(n) ____________________ is a popular software program used to create and manage Internet mailing lists.
ANS: listserv
PTS: 1
21.
_________________________ allows a user to see if people are currently logged in on the network and, if they are, to send them short messages in real time.
ANS:
Instant messaging (IM)
Instant messaging
IM
PTS: 1
22.
The term that has come to represent a business’s commercial dealings over the Internet is ____________________.
ANS: e-commerce
PTS: 1
23.
___________________________________ is the electronic commercial transaction between two or more companies.
ANS:
Electronic data interchange (EDI)
Electronic data interchange
EDI
PTS: 1
24.
A(n) ____________________ is a TCP/IP network inside a company that allows employees to access the company’s information resources through an Internet-like interface.
ANS: intranet
PTS: 1

25.
When an intranet is extended outside the corporate walls to include suppliers, customers, or other external agents, it becomes a(n) ____________________.
ANS: extranet
PTS: 1
ESSAY
1.

How does the Internet Protocol work?

ANS:
The Internet Protocol (IP) provides a connectionless data transfer service over heterogeneous networks by passing and routing IP datagrams. IP datagram is essentially another name for a data packet. To be passed and routed on the Internet, all IP datagrams or packets that are passed down from the transport layer to the network layer are encapsulated with an IP header that contains the information necessary to transmit the packet from one network to another. The format of this header will be explained in the next few paragraphs.
Consider the example of a workstation performing a network operation such as sending an e-mail message to a distant workstation. Suppose both workstations are on local area networks, and the two local area networks are connected via a wide area network. As the local workstation sends the e-mail packet down through the layers of the first internal network, the IP header is encapsulated over the transport layer packet, creating the IP datagram. The appropriate MAC layer headers are encapsulated over the IP datagram, creating a frame, and this frame is sent through LAN 1 to the first router.
Because the router interfaces LAN 1 to a wide area network, the MAC layer information is stripped off, leaving the IP datagram. At this time, the router may use any or all of the IP information to perform the necessary internetworking functions. The necessary wide area network level information is applied, and the packet is sent over the WAN to Router 2. When the packet arrives at the second router, the wide area network information is stripped off, once again leaving the IP datagram. The appropriate MAC layer information is then applied for transfer of the frame over LAN 2, and the frame is transmitted. Upon arrival at the remote workstation, all header information is removed, leaving the original data.
PTS: 1
2.

How does a TCP make a network more reliable?

ANS:
To make a network more reliable, TCP (as well as most transport layer protocols) performs the following six functions:
* Create a connection—The TCP header includes a port address that indicates a particular application on a machine. Used in conjunction, the port address and the IP address identify a particular application of a particular machine. When TCP creates a connection between a sender and a receiver, the two ends of the connection use a port number to identify the particular application’s connection. This port number is found within the TCP datagram and is passed back and forth between sender and receiver.
* Release a connection—The TCP software can also dissolve a connection after all the data has been sent and received.
* Implement flow control—To make sure the sending station does not overwhelm the receiving station with too much data, the TCP header includes a field, called the Window value, that allows the receiver to tell the sender to slow down. This Window value is similar in operation to the sliding window used at the data link layer. The difference between the two window operations is that the data link layer’s

sliding window operates between two nodes or between a workstation and a node, while the TCP window operates between the two endpoints (sender and receiver) of a network connection.
* Establish multiplexing—Because the TCP header includes a port number instead of an IP address, it is possible to multiplex multiple connections over a single IP connection. This multiplexing can be done by creating a different connection that has a port number different from a previous connection.
* Perform error recovery—TCP numbers each packet for transmission with a sequence number. As the packets arrive at the destination site, the receiving TCP software checks these sequence numbers for continuity. If there is a loss of continuity, the receiving TCP software uses an acknowledgment number to inform the sending TCP software of a possible error condition.
* Establish priority—If the sender has to transmit data of a higher priority, such as an error condition,
TCP can set a value in a field (the Urgent Pointer) that indicates that all or a portion of the enclosed data is of an urgent nature.
PTS: 1
3.

How does NAT work?

ANS:
When a user workstation on a company local area network sends a packet out to the Internet, NAT replaces the IP address of the user workstation with a corporate global IP address. In fact, all packets that leave the corporate network contain this global IP address. Thus, the only IP address that anyone sees outside of the corporate network is the one global IP address. If all packets from all workstations leave the corporate network with the same IP address, how do the responses that come back from the
Internet get directed to the proper machine? The NAT software maintains a cache listing of all IP packets that were sent out and who sent each packet. When a response comes back, NAT checks the cache to see who originally sent the request. When NAT finds the match, it removes the global IP address, reinserts the user workstation’s IP address, and places the packet on the corporate network.
What happens if a packet arrives at the corporate NAT software and there is no cache entry with a matching outgoing request? In this case, the packet is destroyed. Apparently, someone has sent a packet to the corporate network that was not requested by a corporate workstation. There is one exception to this rule: If the company is supporting a server, such as a Web server, a packet may originate from a user somewhere out on the Internet. When the Web page request packet arrives at the
NAT software, the IP address where the packet originated will not match any IP addresses in the local cache. Before the NAT software destroys the packet, it examines the message’s destination port number. If the packet is a request for a Web page from the corporate Web server, the NAT software lets the packet in.
PTS: 1
4.

Briefly explain some of the more common HTTP methods.

ANS:
HTTP can perform a number of different commands called methods. A few of the more common methods are the following:
* GET—Retrieves a particular Web page, which is identified by a URL
* HEAD—Uses a given URL to retrieve only the HTTP headers (not the document body) of the Web page * PUT—Sends data from a user’s browser to a remote Web site (this method is used, for example, to send a buyer’s credit card number to a Web merchant during a purchasing transaction) * DELETE—Requests that a server delete the information corresponding to a given URL

PTS: 1
5.

What are the disadvantages of Voice over IP (VoIP)?

ANS:
Voice over IP has a number of disadvantages as well. The statement that sending data over the Internet is essentially free is misleading. Nothing, of course, is free. All Internet users must pay an Internet service provider for access, the interconnecting phone line, and any necessary hardware and software.
Also, even more additional hardware and software is necessary to handle the transmission of voice packets over a corporate data network. Nonetheless, if you already have high-speed Internet access, adding VoIP may be a reasonable way to obtain both local and long-distance telephone service.
A second, and more important disadvantage, is that transmitting voice over a corporate network can be demanding on the network’s resources. If the current corporate network system is straining to deliver data, adding voice to this system can cause severe service problems. These service problems can be compounded because voice systems require networks that can pass the voice data through in a relatively small amount of time. A network that delays voice data by more than 20 milliseconds from end to end will introduce a noticeable echo into the transmission. If the delay becomes longer than 250 milliseconds (that’s only a quarter of a second), the system will be basically unusable.
PTS: 1

Chapter 11: Voice and Data Delivery Networks
TRUE/FALSE
1.
ANS: T
2.
voice signals.
ANS: F
3.
ANS: T
4.
ANS: F
5.
kilometers.
ANS: F

The Internet can transfer conventional data and voice data.
PTS: 1
It wasn’t until the 1950s that POTS began carrying computer data signals as well as
PTS: 1
Only two wires are required to complete a telephone circuit.
PTS: 1
A trunk has a unique telephone number associated with it.
PTS: 1
Subscriber loops usually transmit digital signals, which require amplifiers every few
PTS: 1

6.
Prior to 1984, AT&T (American Telephone and Telegraph) owned all the long-distance telephone lines in the United States.
ANS: T
7.
ANS: T

PTS: 1
Telephone systems were originally designed to transmit the human voice.
PTS: 1

8.
The more information you wish to send over a medium, the lower the frequency of the signal you need to represent that information.
ANS: F

PTS: 1

9.
When they were originally introduced many years ago, dial-up modems were capable of data transfer speeds of merely 15 to 30 bits per second.
ANS: F

PTS: 1

10.
A V.92 modem can place a data connection on hold should someone call the user’s telephone number.
ANS: T

PTS: 1

11.
An asymmetric service is useful for an Internet connection in which the bulk of the traffic comes down from the Internet to the workstation.
ANS: T
12.
ANS: F
13.
ANS: F

PTS: 1
Most residential DSL services are symmetric.
PTS: 1
There is only one DSL format in use today.
PTS: 1

14.
A cable modem is a physical device that separates the computer data from the cable television video signal.
ANS: T
15.
ANS: F
16.
ANS: T
17.

PTS: 1
Cable modem connections are typically symmetric.
PTS: 1
The most popular example of a leased line service is the T-1.
PTS: 1
Quarter-T-1 and half-T-1 lines are called fractional T-1 services.

ANS: T
18.
ANS: F
19.
ANS: F

PTS: 1
The frame relay service can only be a long-distance service.
PTS: 1
Frame relay is called a layer 6 protocol.
PTS: 1

20.
Typically, frame relay is a replacement for the leased lines that connect a business to other businesses or connect multiple offices of the same business.
ANS: T

PTS: 1

21.
Local high-speed telephone connections are almost always less expensive than longdistance, high-speed telephone connections.
ANS: T
22.
ANS: F

PTS: 1
The price of the PVC is inversely proportional to the CIR level.
PTS: 1

23.
Frame relay was originally designed and used to transfer packets of data between two sites more cost effectively than leased lines could.
ANS: T
24.
ANS: F

PTS: 1
ATM transfer rates are as fast as 311 Mbps.
PTS: 1

25.
A real-time interactive application is one of the most demanding with respect to data transmission rate and network throughput.
ANS: T speeds. 26.

ANS: F market. 27.

ANS: T
28.
ANS: F

PTS: 1
DSL and cable modems are more expensive than frame relay systems at comparable
PTS: 1
Convergence has had a particularly noticeable impact on the telecommunications
PTS: 1
ATM clearly dominates in the local area network arena.
PTS: 1

29. lease a PBX.

A company that wishes to have its own in-house telephone system will often buy or

ANS: T
Telnet.

30.

PTS: 1
Frame relay and ATM are losing market share to Internet services such as FTP and

ANS: F

PTS: 1

31.
MPLS on Internet routers and VPNs (virtual private networks) are gaining in popularity in the data network market.
ANS: T

PTS: 1

MULTIPLE CHOICE
1.

The local loop commonly consists of either four or ____ wires.

a.

six

c.

nine

b.

eight

d.

ten

ANS: B
2.

PTS: 1
On the other end of the local loop is the local telephone company’s ____.

a.

trunk

c.

central office

b.

interLATA

d.

intraLATA

ANS: C

PTS: 1

3.
As long as a telephone call remains within a LATA (a(n) ____ call), the telephone call is local and is handled by a local telephone company.
a.

intraLATA

c.

outerLATA

b.

extraLATA

d.

outLATA

ANS: A

PTS: 1

4.
If the telephone call passes out of one LATA and into another (a(n) ____ call), the telephone call is long distance and must be handled by a long-distance telephone company.
a.

intraLATA

c.

inLATA

b.

innerLATA

d.

interLATA

ANS: D

PTS: 1

5.
The telephone network consists of two basic types of telephone lines: a subscriber loop, or standard telephone line, and a ____.
a.

trunk

c.

LATA

b.

CIR

d.

SONET

ANS: A

PTS: 1

6.
After the 1984’s Modified Final Judgment, the long-distance telephone companies became known as ____.
a.
local exchange carriers
c.
interexchange carriers (IECs or IXCs)
(LECs)
b.

central office exchange service ANS: C

d.

private branch exchange (PBXs)

PTS: 1

7.
A(n) ____ is a service from local telephone companies in which up-to-date telephone facilities at the telephone company’s central (local) office are offered to business users, so that they don’t need to purchase their own facilities.
a.

local exchange carriers
(LECs)

c.

interexchange carriers (IECs or IXCs)

b.

central office exchange service d.

private branch exchange (PBXs)

ANS: B
8.

PTS: 1
A(n) ____ handles all in-house calls and places calls onto outside telephone lines.

a.

local exchange carriers
(LECs)

c.

interexchange carriers (IECs or IXCs)

b.

local access transport area
(LATA)

d.

private branch exchange (PBXs)

ANS: D
9.

PTS: 1
____ are permanent direct connections between two specified points.

a.

Tie lines

c.

Centrex

b.

PBXs

d.

IPX

ANS: A

PTS: 1

10.
The Telecommunications Act of 1996 mandated that the existing local telephone companies, now called ____, must give CLECs access to their telephone lines.
a.

private Branch Exchange (PBX)

b.

Centrex (central office exchange service)

c.

incumbent local exchange carriers (ILECs)

d.

interexchange carriers (IECs)

ANS: C

PTS: 1

11.
The ____ standard is a 56,000-bps dial-up modem standard approved by a standardsmaking organization rather than a single company.
a.

R.56

c.

802.11Q

b.

V.90

d.

ANS: B
12.

803.1

PTS: 1
A(n) ____ connection is one in which the transfer speeds in both directions are equal.

a.

symmetric

c.

static

b.

asymmetric

d.

dynamic

ANS: A speed. 13.

PTS: 1
A(n) ____ connection has a faster downstream transmission speed than its upstream

a.

symmetric

c.

asymmetric

b.

static

d.

dynamic

ANS: C circuit. 14.

PTS: 1
Because DSL is an always-on connection, it uses a ____ circuit instead of a switched

a.

changing

c.

virtual

b.

dynamic

d.

permanent

ANS: D

PTS: 1

15.
When no splitter is used to separate the DSL signal from the POTS signal, then the service is called ____.
a.

asymmetric DSL

c.

symmetric DSL

b.

splitterless DSL

d.

POTSless DSL

ANS: B
____.

16.

PTS: 1
Digital subscriber line comes in a variety of formats. Often collectively referred to as

a.

ADSL

c.

SDSL

b.

CDSL

d.

xDSL

ANS: D

PTS: 1

17.
____ is a popular format that transmits the downstream data at a faster rate than the upstream rate.
a.

Asymmetric digital subscriber line (ADSL)

b.

Consumer DSL (CDSL)

c.

DSL Lite

d.

High bit-rate DSL (HDSL)

ANS: A

PTS: 1

18.
____ is a trademarked version of DSL with speeds that are a little slower than typical
ADSL speeds.
a.
Asymmetric digital subscriber line (ADSL)
b.

DSL Lite

c.

Consumer DSL (CDSL)

d.

High bit-rate DSL (HDSL)

ANS: C
19.

PTS: 1
____ is the earliest form of DSL.

a.

DSL Lite

c.

Very high data rate DSL (VDSL)

b.

High bit-rate DSL
(HDSL)

d.

Rate-adaptive DSL (RADSL)

ANS: B

PTS: 1

20.
____ is a format in which the transfer rate can vary, depending on noise levels within the telephone line’s local loop.
a.

DSL Lite

c.

Very high data rate DSL (VDSL)

b.

High bit-rate DSL
(HDSL)

d.

Rate-adaptive DSL (RADSL)

ANS: D

PTS: 1

21.
A ____ service is an all-digital connection that can transfer either voice or data at speeds up to 1.544 Mbps.
a.

T-1

c.

T-3

b.

T-2

d.

T-4

ANS: A lines. 22.

PTS: 1
____ is a packet-switched network that was designed for transmitting data over fixed

a.

T-1

c.

Frame relay

b.

IntraLATA

d.

InterLATA

ANS: C

PTS: 1

23.
The designation layer ____ protocol means that frame relay technology is only one part of a network application and resides at the data link layer.
a.

2

c.

4

b.

3

d.

6

ANS: A

PTS: 1

24.
When a customer establishes a permanent virtual circuit with a frame relay carrier, both customer and carrier agree on a data transfer rate called the ____.

a.

bit rate

c.

committed information rate (CIR)

b.

PVC rate

d.

LATA rate

ANS: C

PTS: 1

25.
The ____ allows the customer to exceed the committed information rate by a fixed amount for brief moments of time.
a.

bit rate

c.

committed information rate (CIR)

b.

burst rate

d.

LATA rate

ANS: B
____.

26.

PTS: 1
Before ATM can transfer any data, you must first create a logical connection called a

a.

virtual path connection
(VPC)

c.

network-network interface

b.

virtual channel connection (VCC)

d.

network-user interface

ANS: B
27.

PTS: 1
A ____ is a bundle of VCCs that have the same endpoints.

a.

virtual path connection
(VPC)

c.

network-network interface

b.

virtual interface connection (VIC)

d.

network-user interface

ANS: A
28.

PTS: 1
When a VCC transmits network management and routing signals, it is called the ____.

a.

virtual path connection
(VPC)

c.

network-network interface

b.

virtual interface connection (VIC)

d.

network-user interface

ANS: C
29.

PTS: 1
____ is the most expensive ATM class of service.

a.

Variable bit rate (VBR)

c.

Unspecified bit rate (UBR)

b.

Available bit rate (ABR)

d.

Constant bit rate (CBR)

ANS: D

PTS: 1

30.
____ applications often send bursts of data, and the ATM network guarantees that its traffic is delivered on time.
a.

Variable bit rate (VBR)

c.

Unspecified bit rate (UBR)

b.

Available bit rate (ABR)

d.

Constant bit rate (CBR)

ANS: A

PTS: 1

31.
____ is capable of sending traffic that may experience bursts of data, but there are no promises as to when the data may be sent.
a.
Variable bit rate (VBR)
c.
Unspecified bit rate (UBR)
b.

Available bit rate (ABR)

ANS: C

d.

Constant bit rate (CBR)

PTS: 1

32.
____ means that users utilize a single desktop application to send and receive e-mail, voice mail, and fax.
a.

Interactive voice response

c.

Fax processing

b.

Unified messaging

d.

Third-party call control

ANS: B

PTS: 1

33.
____ means that a user calling into a company telephone system provides some form of data by speaking into the telephone, and a database query is performed using this spoken information. a.

Third-party call control

b.

Unified messaging

c.

Fax-back

d.

Integrated voice recognition and response

ANS: D

PTS: 1

34.
In ____, a fax image that is stored on a LAN server’s hard disk can be downloaded over a local area network, converted by a fax card, and sent out to a customer over a trunk.
a.

third-party call control

c.

fax processing

b.

unified messaging

d.

integrated voice recognition and response

ANS: C

PTS: 1

35.
____ means that users have the ability to control a call—for example, set up a conference call—without being a part of it.
a.

Third-party call control

b.

Unified messaging

c.

Fax-back

d.

Integrated voice recognition and response

ANS: A

PTS: 1

36.
____ means that different icons on a computer screen represent common PBX functions such as call hold, call transfer, and call conferencing, making the system easier for operators to use.
a.

Third-party call control

c.

Fax-back

b.

PBX graphic user interface ANS: B
37.

d.

Call filtering

PTS: 1
____ means that users can specify telephone numbers that are allowed to get through.

a.

PBX graphic user interface c.

Fax-back

b.

Customized menuing system d.

Call filtering

ANS: D
38.

PTS: 1
MPLS and VPNs continue to replace which long-distance data services?

a.

Google and Yahoo

c.

frame relay and ATM

b.

Telnet and FTP

d.

frame relay and FTP

ANS: C

PTS: 1

COMPLETION
1.
The basic telephone system, or ________________________________________, has been in existence since the early 1900s.
ANS:
plain old telephone service (POTS) plain old telephone service
POTS
PTS: 1
2.

The ____________________ is the telephone line that leaves your house or business.

ANS: local loop
PTS: 1
3.
The ____________________ contains the equipment that generates a dial tone, interprets the telephone number dialed, checks for special services, and connects the incoming call to the next point.
ANS:
central office (CO) central office
CO
PTS: 1
4.
A(n) ___________________________________ is a geographic area such as a large metropolitan area or part of a large state and determines whether a telephone call is local or long distance. ANS: local access transport area (LATA) local access transport area
LATA
PTS: 1
5.
A(n) ____________________ does not have a telephone number associated with it, because it can carry hundreds of voice and data channels.
ANS: trunk
PTS: 1
6.
Immediately after the breakup of AT&T there were 7 Regional Bell Operating
Companies (RBOCs). As of year-end 2009, there are ____________________ RBOCs.
ANS:
3 three PTS: 1
7.
After the 1984’s Modified Final Judgment, the local telephone companies became known as ______________________________.
ANS:
local exchange carriers (LECs) local exchange carriers
LECs
PTS: 1
8.
A(n) ______________________________ is a large, computerized, self-contained telephone system that sits in a telephone room on a company’s premises.
ANS:
Private Branch Exchange (PBX)
Private Branch Exchange
PBX
PTS: 1 dialing. 9.

ANS: Private
PTS: 1

____________________ lines and tie lines are leased telephone lines that require no

10.
The ______________________________ paved the way for anybody to offer a local telephone service to homes and businesses.
ANS: Telecommunications Act of 1996
PTS: 1
11.
After the Telecommunication Act of 1996, new providers of local telephone services were called _____________________________________________.
ANS:
competitive local exchange carriers (CLECs) competitive local exchange carriers
CLECs
PTS: 1
12.
Shortly after V.90 was introduced,
_____________________________________________ introduced the V.92 modem standard.
ANS:
International Telecommunication Union (ITU)
International Telecommunication Union
ITU
PTS: 1
13.
_________________________ is a technology that allows existing twisted pair telephone lines to transmit multimedia materials and high-speed data.
ANS: Digital subscriber line
PTS: 1
14.
____________________ is a slower format compared to ADSL; also known as
Universal DSL, G.Lite, and splitterless DSL.
ANS: DSL Lite
PTS: 1
15.
______________________________ is also known as very high-speed DSL and very high bit-rate DSL.
ANS:
Very high data rate DSL (VDSL)
Very high data rate DSL
VDSL
PTS: 1

16.
A(n) ____________________ is a high-speed communications service that allows high-speed access to wide area networks such as the Internet via a cable television connection.
ANS: cable modem
PTS: 1
17.
The permanent connection in a frame realy network that is necessary to transfer data between two endpoints is called a(n) ___________________________________.
ANS:
permanent virtual circuit (PVC) permanent virtual circuit
PVC
PTS: 1
18.
______________________________ , like frame relay, is a very high-speed, packetswitched service that is offered by the telephone companies.
ANS: Asynchronous Transfer Mode
PTS: 1
19.
When a VCC transmits user-to-network control signaling, the connection is called the
_________________________.
ANS: user-network interface
PTS: 1
20.
A(n) ____________________ is a definition of a type of traffic and the underlying technology that will support that type of traffic.
ANS: class of service
PTS: 1
21.
The ATM _________________________ class of service is used for traffic that may experience bursts of data, and whose bandwidth range is roughly known, such as that of a corporate collection of leased lines.
ANS:
Available bit rate (ABR)
Available bit rate
ABR
PTS: 1
22.
________________________________________ is a relatively new field that combines more traditional voice networks with modern computer networks.

ANS:
Computer-telephony integration (CTI)
Computer-telephony integration
CTI
PTS: 1
23.
______________________________ means that when a customer calls your company, his or her telephone number is used to extract the customer’s records from a corporate database. ANS: Interactive voice response
PTS: 1
24.
_____________________________________________ mean that as a person speaks into a telephone, the system can digitize the voice and store it on a hard disk drive as computer data.
ANS: Text-to-speech and speech-to-text conversion
PTS: 1

ESSAY
1.

What was the reasoning behind the development of CLECs?

ANS:
The reasoning behind the development of CLECs was fairly straightforward and meant to better accommodate the way phone services were already being delivered. For example, in some areas of the country, local cable television companies already offered local telephone service. Because a majority of homes and businesses in the United States are already wired for cable television, allowing cable companies in other areas to offer local telephone service over those same cable TV lines seemed like a reasonable idea. Termed cable-telephone or cable telephony, telephone services over cable television lines are now offered by most of the major cable television companies— including Cox
Communications and Comcast, as well as many smaller cable companies—in most major cities across the country. In fact, large cable companies in the U.S. are achieving penetration rates of as high as 10 to 20 percent in their particular markets. Of new subscribers, 95 percent are dropping their old local telephone service in favor of the new cable service, and some reports indicate that the number of cable telephony subscribers in 2005 exceeded 14 million, with 22 million predicted by the end of 2008. The medium that delivers cable telephony is a hybrid of fiber and coaxial cable called Hybrid Fiber Coax, or HFC. This technology can also deliver cable modem service into homes and businesses.
PTS: 1
2.

How does a 56k dial-up modem work?

ANS:
The new 56k modems are a hybrid design, combining analog signaling and digital signaling. The upstream connection from modem to remote end still uses conventional analog signaling and modulation techniques, and thus is limited to a maximum transmission speed of 33,600 bps. The downstream link, however, is where the 56k modem really stands out. Instead of using analog signaling, the 56k modem employs digital signaling. The telephone system has actually been using

digital signaling over telephone lines for many years. In fact, the telephone system can send an 8-bit sample 8000 times per second, which corresponds to 64,000 bits per second, or 64 kbps. If the telephone company can transmit 64 kbps, does this mean that we users can receive a 64-kbps downstream signal? Unfortunately, the answer is “No.” When the telephone company transmits a digital 64-kbps telephone signal, the signal is transmitted digitally from one switching center to another. But when a telephone signal is transmitted into our homes and small businesses, it must be adjusted so that it can traverse the local loop. The local loop is the stretch of telephone wire that runs between a house (or small business) and the telephone company’s central office. This local loop is analog and can support only analog signaling.
Before the telephone signal is transmitted over the local loop, the central office converts the digital signal to an analog signal. When the analog signal enters your house, your computer’s 56k modem converts the analog signal back to digital data, because computers manipulate digital data. When an analog signal is converted to digital data, quantizing noise is introduced. The presence of this noise is the reason it is not possible to transmit a 64-kbps data stream into the local loop. But a smaller data stream, of approximately 56 kbps, is possible.
PTS: 1
3.

What does a business or home user need to establish a DSL connection?

ANS:
At the present time, four components are required. The local telephone company (LEC) must install a special router called a DSLAM (digital subscriber line access multiplexer) within the telephone company’s central office. This device bypasses the central office switching equipment and creates and decodes the DSL signals that transfer on the telephone local loop. Next, the local telephone company may also install a DSL splitter on its premises, which combines or splits the DSL circuits (the upstream and downstream channels) with the standard telephone circuit of POTS. Some DSL systems transmit over the same telephone line that runs from a central office to a home or business. Because it is the same telephone line, DSL must share the line with a POTS signal.
On the user end, a DSL modem is required to convert the DSL signals into a form that the user workstation or network can understand. If the DSL circuit is also carrying a POTS telephone circuit, the user will also need a splitter to separate the regular telephone line from the DSL data line. Finally, the DSLAM router at the telephone company’s central office must be connected to an Internet service provider via a high-speed line. Because this highspeed line will be supporting the Internet service requests from multiple users, the line needs to be a very fast service, such as ATM.
PTS: 1
4.

What are the advantages of frame relay?

ANS:
A frame relay service provides many attractive alternatives to leased lines. One of the first noticeable characteristics of a frame relay network is its very high transfer speeds. The data transfer speeds can be very fast, up to 45 Mbps and sometimes even higher. Along with the high data transfer rates, there is high throughput—the network as a whole is also very fast. Using fiber-optic cables, frame relay switches quickly transfer data so that it travels from one end of the network to the other in a relatively short period of time. Frame relay networks also provide very good security. Because of the encryption techniques used to transmit data between frame relay switches, it is extremely difficult to intercept and decode the transmitted data. In addition, frame relay connections are permanent connections. Because the connection is fixed, it is always available.

Another advantage associated with frame relay (and other modern high-speed wide area networks) is that their error rates during transmission are low. In fact, the error rate of frame relay networks is so low that the network does not have any form of error control. If an error occurs, the frame relay network simply discards the frame. It is the responsibility of the application, and not the frame relay network, to perform error control.
Last, frame relay networks are reasonably priced. Fixed monthly pricing is based on three charges: a port charge for each access line that connects a business into the frame relay network; a charge for each permanent connection that runs through the frame relay network between two endpoints
(companies using the service); and a charge for the access line, which is the high-speed telephone line that physically connects the business to the frame relay port. Because a port and access line are capable of supporting multiple permanent connections, a user may pay one port charge, one access line charge, and several permanent connection charges.
Recently, frame relay network are starting to lose ground to MPLS over Internet routers and virtual private networks (VPNs).
PTS: 1
5.

What are the advantages and disadvantages of ATM?

ANS:
Due to its range of features, such as high transfer speeds, various classes of service, and ability to operate over many types of media and network topologies (LANs as well as WANs), ATM has a number of significant advantages. ATM can support a wide range of applications with varying bandwidths, at a wide range of transmission speeds. Cell switching, which is performed by ATM’s high-speed, hardware-based switches that route cells down the appropriate path, is so fast that it provides short delays and high bandwidths. ATM’s different classes of service allow customers to choose service type and pricing individually for each data connection (VCC). Finally, ATM is extremely versatile. It can carry voice, packet data, and video over the same facilities.
As you might expect, ATM also has a number of disadvantages. It is often more expensive than other data transmission options. The cost of ATM equipment is high. This is because the cell-switching equipment, to be capable of delivering such a fast connection, is by necessity relatively complex. Due to the complexity of ATM, there is a high learning curve for setting up and managing the network.
Lastly, compatible hardware and software may not be widely available.
ATM is now being heavily used by the large telecommunications carriers (AT&T, Sprint, and so on) to provide voice and Internet services. Because of its complexity and cost, smaller businesses have been reluctant to use ATM. Alternate technologies that can offer reasonably comparable speeds at much lower costs have, however, attracted much attention from smaller businesses. One attractive alternative to ATM on a local area network is high-speed Ethernet, which has transfer speeds hitting 100 Mbps to
10 Gbps. Metropolitan area networks are also seeing a growth in high-speed Ethernet, as it is chosen over ATM.
Recently, ATM network are starting to lose ground to MPLS over Internet routers and virtual private networks (VPNs).
PTS: 1

Chapter 12: Network Security

TRUE/FALSE
1.
ANS: F

Internet systems are the only systems that experience security problems.
PTS: 1

2.
The two leading attack methods for the last few years have exploited known vulnerabilities in operating systems and in application software.
ANS: T
3.
ANS: T
4.
ANS: F
5.
ANS: T

PTS: 1
A worm is a form of computer virus.
PTS: 1
All system attacks need a user to open an e-mail or Web page.
PTS: 1
Pings are used most commonly by Unix-based systems.
PTS: 1

6.
A popular attack method is to abuse or take advantage of valid user accounts and the permissions associated with those accounts.
ANS: T

PTS: 1

7.
The physical protection of a computer system or a computer network consists of protecting the equipment from physical damage.
ANS: T
8.
ANS: F
9.
ANS: T

PTS: 1
Expensive computer systems should always be placed in the basements of buildings.
PTS: 1
Many employees feel surveillance is an intrusion into their privacy.
PTS: 1

10.
Controlling access to a computer network involves deciding and then limiting who can use the system and when the system can be used.
ANS: T
11.
company.
ANS: F

PTS: 1
Top-level executives often have access to a narrow range of information within a
PTS: 1

12. passwords. ANS: T
13.
ANS: F

One of the most common ways to control access to a system is to require user IDs and
PTS: 1
Rarely, passwords become known, or “misplaced,” and fall into the wrong hands.
PTS: 1

14.
Some computer systems generate random passwords that are very difficult to guess, but are also hard to remember.
ANS: T

PTS: 1

15.
Because of security concerns, modern network operating systems do not allow network administrators to create workgroups.
ANS: F
16.
ANS: T
17.
ANS: T

PTS: 1
Auditing a computer system is often a good way to deter crime.
PTS: 1
Early cryptography algorithms used the same key for both encryption and decryption.
PTS: 1

18.
One of the inherent problems with protecting a single key is that it means that only one key is used to both encode and decode the message.
ANS: T

PTS: 1

19.
Both SSL and IPsec may eventually give way to S-HTTP, the newer security standard created by the Internet Engineering Task Force.
ANS: F
20.
ANS: T
21.
ANS: F

PTS: 1
One popular application of IPsec is in the support of virtual private networks.
PTS: 1
The DES algorithm works with 128-bit blocks of data.
PTS: 1

22.
The National Institute of Standards and Technology selected the algorithm Lucifer in
October 2000 as the basis for AES.
ANS: F
23.
ANS: T

PTS: 1
To authenticate electronic documents as yours, you need to create a digital signature.
PTS: 1

24.

One of the primary functions of Kerberos is to authenticate users.

ANS: T
25.

PTS: 1
All certificates are issued by a certificate authority.

ANS: T
26.

PTS: 1
If you exclusive-OR a 0 and a 0, the result is 1.

ANS: F

PTS: 1

27.
A firewall cannot limit users on the Internet from accessing certain portions of a corporate network.
ANS: F

PTS: 1

28.
A packet filter firewall is a computer running proxy server software, whose function is much like that of a librarian who controls access to books in a library’s rare books room.
ANS: F
29.

PTS: 1
A proxy server sits inside a company’s corporate network.

ANS: F
30.

PTS: 1
WAP has been replaced by a new standard, Wired Equivalency Protocol (WEP).

ANS: F

PTS: 1

MULTIPLE CHOICE
1.
One very common technique to attack a system is to deliver an e-mail or Web page that contains a malicious piece of code called a ____.
a.

NOS

c.

proxy

b.

firewall

d.

mobile malicious code

ANS: D
2.

PTS: 1
Many people consider the Trojan horse to be a form of computer ____.

a.

virus

c.

router

b.

firewall

d.

switch

ANS: A

file.
a.

3.

PTS: 1
A ____ virus is a common type of virus that is programmed into an attached macro

boot sector

c.

polymorphic

b.

macro

d.

ANS: B

file infector

PTS: 1

4.
A ____ virus is usually stored on some form of removable media. When the removable media (such as a flash drive) is connected to a new machine and is used to boot the machine, the virus moves from the media into the host system.
a.

polymorphic

c.

boot sector

b.

macro

d.

file infector

ANS: C
5.

PTS: 1
A ____ virus mutates with every infection, thus making them difficult to locate.

a.

polymorphic

c.

boot sector

b.

macro

d.

file infector

ANS: A file. 6.

PTS: 1
A ____ virus is a virus that infects a piece of executable code such as an .exe or .com

a.

polymorphic

c.

boot sector

b.

macro

d.

file infector

ANS: D storm. 7.

PTS: 1
Some common types of denial of service include e-mail bombing, ____, and ping

a.

firewalling

c.

smurfing

b.

filtering

d.

routing

ANS: C

PTS: 1

8.
If e-mail messages have a return address of someone other than the person actually sending the e-mail, then the sender is ____.
a.

e-mail bombing

c.

smurfing

b.

spoofing

d.

firewalling

ANS: B

PTS: 1

9.
____ is the name of a particularly nasty automated program that attacks a network by exploiting Internet Protocol (IP) broadcast addressing and other aspects of Internet operation.
a.

E-mail bombing

c.

Smurfing

b.

Spoofing

d.

Firewalling

ANS: C

PTS: 1

10.
A ____ is a common Internet tool used to verify if a particular IP address of a host exists and to see if the particular host is currently available.

a.

ping

c.

router

b.

firewall

d.

DNS

ANS: A

PTS: 1

11.
In ____, a Web user seeking to visit a particular company’s Web site is unknowingly redirected to a bogus Web site that looks exactly like that company’s official Web site.
a.

smurfing

c.

worming

b.

pharming

d.

e-mail bombing

ANS: B
12.

PTS: 1
____ may be considered a form of physical protection.

a.

Router

c.

Trojan horses

b.

Worms

d.

Surveillance

ANS: D
13.
their systems.

PTS: 1
____ involves electronically monitoring data flow and system requests into and out of

a.

Worms

c.

Firewalls

b.

Intrusion detection

d.

Routers

ANS: B

PTS: 1

14.
Perhaps the most common form of protection from unauthorized use of a computer system is the ____.
a.

password

c.

PKI

b.

certificate

d.

digital signature

ANS: A

PTS: 1

15.
____ usually involves having a software program that monitors every transaction within a system.
a.

Firewalling

c.

Access rights

b.

Routing

d.

Computer auditing

ANS: D

PTS: 1

16.
____ cable represented a major improvement in the ability of transmission media to secure sensitive data.
a.

Coaxial

c.

Fiber-optic

b.

Twisted

d.

Copper

ANS: C
17.

PTS: 1
____ is data before any encryption has been performed.

a.

Plaintext

c.

Encriptext

b.

Ciphertext

d.

Cryptotext

ANS: A
18.

PTS: 1
A(n) ____ is the computer program that converts plaintext into an enciphered form.

a.

worm

c.

firewall

b.

Trojan horse

d.

encryption algorithm

ANS: D

PTS: 1

19.
A(n) ____ is the unique piece of information that is used to create ciphertext and then decrypt the ciphertext back into plaintext.
a.

encryption algorithm

c.

key

b.

firewall

d.

IP address

ANS: C

PTS: 1

20.
A ____ substitution-based cipher replaces a character or group of characters with a different character or group of characters.
a.

transposition

c.

monotransposition

b.

monoalphabetic

d.

polytransposition

ANS: B
21.

PTS: 1
Possibly the earliest example of a polyalphabetic cipher is the ____ cipher.

a.

Caesars

c.

Enigma

b.

Roman

d.

Vigenére

ANS: D

PTS: 1

22.
A ____ cipher is different from a substitution-based cipher in that the order of the plaintext is not preserved.
a.

transposition-based

c.

polyalphabetic

b.

monoalphabetic

d.

multialphabetic

ANS: A
23.

PTS: 1
The concept of two keys, public and private, is called ____ cryptography.

a.

private key

c.

secret key

b.

public key

d.

symmetric

ANS: B

PTS: 1

24.
The opposite of asymmetric encryption is ____ encryption, in which one key is used to encrypt and decrypt.

a.

available key

c.

symmetric

b.

asymmetric key

d.

public key

ANS: C

PTS: 1

25.
SSL’s successor is ____, which is based upon SSL version 3 and contains a few technical improvements over SSL.
a.

Transport Layer Security
(TLS)

c.

Date Encryption Standard (DES)

b.

IPsec

d.

Advanced Encryption Standard (AES)

ANS: A
26.

PTS: 1
____ is a set of protocols created to support the secure transfer of data at the IP layer.

a.

Transport Layer Security
(TLS)

c.

Date Encryption Standard (DES)

b.

IPsec (IP security)

d.

Advanced Encryption Standard (AES)

ANS: B

PTS: 1

27.
The ____ is a commonly employed encryption method used by businesses to send and receive secure transactions.
a.

firewall

c.

Data Encryption Standard (DES)

b.

Trojan horse

d.

TCP

ANS: C

PTS: 1

28.
A ____ is a security procedure that uses public key cryptography to assign to a document a code for which you alone have the key.
a.

certificate

c.

PKI

b.

certificate authority

d.

digital signature

ANS: D

PTS: 1

29.
____ is high-quality encryption software that has become quite popular for creating secure e-mail messages and encrypting other types of data files for average users.
a.

DES

c.

3DES

b.

PGP

d.

AES

ANS: B

PTS: 1

30.
____ is an authentication protocol designed to work on client/server networks that use secret or symmetric cryptography.
a.

Kerberos

c.

3DES

b.

DES

d.

AES

ANS: A

PTS: 1

31.
____ is the combination of encryption techniques, software, and services that involves all the necessary pieces to support digital certificates, certificate authorities, and public key generation, storage, and management.
a.
3DES
c.
Data Encryption Standard (DES)
b.

Advanced Encryption
Standard (AES)

ANS: D
32.

d.

Public key infrastructure (PKI)

PTS: 1
Many certificates conform to the ____ standard.

a.

X.309

c.

X.509

b.

X.409

d.

X.609

ANS: C

PTS: 1

33.
A ____ is a list of certificates that have been revoked before their originally scheduled expiration date.
a.

PKI

c.

digital certificate

b.

public key cryptography

d.

certificate revocation list (CRL)

ANS: D

PTS: 1

34.
____ technology essentially takes the data to be transmitted and rather than transmitting it in a fixed bandwidth spreads it over a wider bandwidth.
a.

Spread spectrum

c.

AES

b.

3DES

d.

PKI

ANS: A

PTS: 1

35.
____ spread spectrum spreads the transmission of a signal over a wide range of frequencies using mathematical values.
a.

Frequency hopping

c.

Time hopping

b.

Direct sequence

d.

Amplitude sequence

ANS: B
36.

PTS: 1
____ scanning works by recognizing the unique pattern of a virus.

a.

Time-based

c.

Signature-based

b.

Amplitude-based

d.

Frequency-based

ANS: C

PTS: 1

37.
An antivirus technique that is used in conjunction with signature-based scanning and terminate-and-stay-resident monitoring is ____.
a.

integrity checking

c.

direct sequence

b.

time division

d.

frequency hopping

ANS: A

PTS: 1

38.
The ____ firewall is essentially a router that has been programmed to filter out certain
IP addresses or TCP port numbers.
a.
proxy server
c.
packet filter
b.

switch

d.

ANS: C
39.

hub

PTS: 1
The first security protocol for wireless LANs was ____.

a.

Wi-Fi Protected Access
(WPA)

c.

IPsec

b.

Wired Equivalency
Protocol (WEP)

d.

IEEE 802.11i

ANS: B

PTS: 1

40.
IEEE ____ addresses both weaknesses of WEP by allowing the keys, encryption algorithms, and negotiation to be dynamically assigned, and by adopting the AES encryption based on the Rijndael algorithm with 128-, 192-, or 256-bit keys.
a.

802.11a

c.

802.11g

b.

802.11b

d.

802.11i

ANS: D

PTS: 1

COMPLETION
1.
A mobile malicious code is also known as ____________________ because it is hiding inside a harmless-looking piece of code.
ANS: Trojan horse
PTS: 1
2.
A computer ____________________ is a small program that alters the way a computer operates without the knowledge of the computer’s users and often does various types of damage. ANS: virus
PTS: 1
3.
A computer ____________________ is a program that copies itself from one system to another over a network, without the assistance of a human being.
ANS: worm
PTS: 1

4.
_________________________ bombard a computer site with so many messages that the site is incapable of performing its normal duties.
ANS: Denial of service attacks
PTS: 1
5.
In ____________________, a perpetrator sends an excessive amount of unwanted email messages to someone.
ANS: e-mail bombing
PTS: 1
6.
A(n) ____________________ is a condition in which the Internet ping program is used to send a flood of packets to a server to make the server inoperable.
ANS: ping storm
PTS: 1
7.
When hackers will even go so far as to create an application that appears to be legitimate and prompts users for an ID and password, the type of attack is termed
____________________.
ANS: phishing
PTS: 1
8.
In computer terminology, a(n) ____________________ is a trap that is set by network personnel in order to detect unauthorized use of a network resource.
ANS: honeypot
PTS: 1

access.

9.

____________________ define the network resources that a user or set of users can

ANS: Access rights
PTS: 1
10.
____________________ techniques that observe and record some aspect of the user, such as voiceprints, fingerprints, eyeprints, and faceprints, appear to be the wave of the future to replace passwords.
ANS: Biometric
PTS: 1

11. techniques. ____________________ is the study of creating and using encryption and decryption

ANS: Cryptography
PTS: 1 applied. 12.

The ____________________ is the data after the encryption algorithm has been

ANS: ciphertext
PTS: 1
13.
The ____________________ substitution-based cipher uses multiple alphabetic strings to encode the plaintext, rather than one alphabetic string.
ANS: polyalphabetic
PTS: 1
14.

The ____________________ cipher was devised by Blaise de Vigenére in 1586.

ANS: Vigenére
PTS: 1
15.

Public key cryptography is also called ____________________ encryption.

ANS: asymmetric
PTS: 1
16.
____________________ (SSL) is an additional layer of software added between the application layer and the transport (TCP) layer that creates a secure connection between sender and receiver. ANS: Secure Sockets Layer
PTS: 1
17.
With ____________________, the data is encrypted using
DES three times—the first time by a first key, the second time by a second key, and the third time by the first key again.
ANS: triple-DES
PTS: 1
18.
The ___________________________________ was selected by the U.S. government to replace DES.
ANS:

Advanced Encryption Standard (AES)
Advanced Encryption Standard
AES
PTS: 1
19.
In an effort to create an encryption scheme that could be used by the average person, an entrepreneur named Philip Zimmermann created encryption software called
_________________________.
ANS:
Pretty Good Privacy (PGP)
Pretty Good Privacy
PGP
PTS: 1
20.
A digital certificate, or simply a(n) ____________________, is an electronic document, similar to a passport, that establishes your credentials when you are performing transactions on the World Wide Web.
ANS: certificate
PTS: 1
21.
A(n) ______________________________ is either specialized software on a network or a trusted third-party organization or business that issues and manages certificates.
ANS:
certificate authority (CA) certificate authority
CA
PTS: 1
22.
____________________ is the art and science of hiding information inside other, seemingly ordinary messages or documents.
ANS: Steganography
PTS: 1
23.
The idea behind ____________________ spread spectrum transmission is to bounce the signal around on random frequencies rather than transmit it on one fixed frequency.
ANS: frequency hopping
PTS: 1
24.
Antivirus software with ________________________________________ runs in the background while an application that the user is executing runs in the foreground.
ANS: terminate-and-stay-resident monitoring

PTS: 1
25.
A(n) ____________________ is a system or combination of systems that supports an access control policy between two networks.
ANS: firewall
PTS: 1
ESSAY
1.

How does phishing work?

ANS:
One common attack method is to try to guess or intercept valid IDs and passwords from authorized users. Hackers will try to steal passwords by guessing simple combinations or eavesdropping on transmissions in which a password is being transmitted. Some hackers will even go so far as to create an application that appears to be legitimate and prompts users for an ID and password. Once an individual enters his or her ID and password, the software displays a message that gives the appearance of a system failure. The user moves on, not knowing that his or her ID and password have just been passed to a bogus program. In the last few years, there have been a number of attempts to steal IDs and passwords. In several instances, hackers created an e-mail that seemed to be a legitimate request coming from a well-known company. The e-mail even included the official-looking corporate logos and emblems. In the e-mail, the unsuspecting user was asked to provide private information such as a Social Security number or credit card number. The hacker would collect this personal information and use it illegally to purchase items or, even worse, commit identity theft.
PTS: 1
2.

What are some of the standard rules for creating or changing a password?

ANS:
The standard rules that an individual should follow when creating or changing a password include:
* Change your password often.
* Pick a good password by using at least eight characters, mixing uppercase and lowercase if the computer system is case-sensitive, and mixing letters with numbers.
* Don’t choose passwords that are similar to your first or last names, pet names, car names, or other choices that can be easily guessed.
* Don’t share your password with others; doing so invites trouble and misuse.
PTS: 1 users. 3.

Describe some examples of systems that use biometric techniques to authenticate

ANS:
England has a large database of earprints. Research shows that no two ears are the same; thus, an earprint is useful in helping to identify an individual. Fingerprints have, of course, long been used to distinguish one individual from another. Now, desktop devices the size of a computer mouse can scan a user’s thumbprint and allow or disallow the user access to a computer system. Systems also are available that can record and digitize your voice. The digital voice pattern is compared to a stored

sample, and the software determines if the match is close enough for validation. Retinal scans (the retina is the inside back lining of the eye) have been commonly featured in movies and do exist in the real world as a security technique, although to a small degree due to complexity and cost. An additional impediment has been that people are squeamish when told a laser is going to scan the inside of their eyeballs. Another part of the eye that is unique among all individuals is the iris, or the colored portion of the eye. Some security devices use the iris to identify people who are allowed to access a given system. Because the technology needed to perform iris scans is less expensive than retinal scan technology, it is more likely that we will see iris scans performed in the near future. Other research in the field of biometric techniques has been aimed at digitizing the features of the entire face and comparing this digital representation with a stored image. Companies that manufacture 24-hour automatic teller machines are interested in replacing the credit-card-sized automatic teller machine
(ATM) card and corresponding PIN with something that cannot be as easily stolen, such as a fingerprint, faceprint, or eyeprint. To enhance their security, many companies require combinations of forms of identification, such as a password and a thumbprint.
PTS: 1
4.

How does public key cryptography work?

ANS:
Consider a business that has its headquarters in New York. A branch office in Atlanta wishes to send secure data to the New York office. The New York office sends the public key to Atlanta and keeps the private key locked up safe in New York. The Atlanta office uses the public key to encrypt the data, and sends the encrypted data to New York. Only the New York office can decode the data, because it is the only one possessing the private key. Even if other parties intercept the transmission of the public key to Atlanta, nothing will be gained, because it is not possible to deduce the private key from the public key. Likewise, interception of the encrypted data will lead to nothing, because the data can be decoded only with the private key.
For a more familiar example, consider a situation in which a person browsing the Web wishes to send secure information (such as a credit card number) to a Web server. The user at a workstation clicks on a secured Web page and sends the appropriate request to the server. The server returns a “certificate,” which includes the server’s public key, and a number of preferred cryptographic algorithms. The user’s workstation selects one of the algorithms, generates a set of public and private keys, keeps the private key, and sends the public key back to the server. Now both sides have their own private keys, and they both have each other’s public key. Data can now be sent between the two endpoints in a secure fashion. PTS: 1
5.

What information does a certificate contain?

ANS:
All X.509 certificates contain the following pieces of information:
* Version—Identifies the version of the X.509 standard that applies to this certificate
* Serial number—A unique value that identifies a particular certificate; when a certificate is revoked, its serial number is placed in a certificate revocation list (CRL)
* Signature algorithm identifier—Identifies the algorithm used by the certificate authority (an entity that will be defined shortly) to sign the certificate
* Issuer name—The name of the entity, normally a certificate authority, that signed the certificate (in some instances, the issuer signs his or her own name)

* Validity period—The limited amount of time for which each certificate is valid (a period that can be as short as a few seconds or as long as a century), denoted by a start date and time and an end date and time * Subject name—The name of the entity whose public key this certificate identifies
* Subject public key information—The public key of the entity being named, together with an algorithm identifier that specifies to which public key encryption system this key belongs
* Digital signature—The signature of the certificate authority that will be used to verify a legitimate certificate PTS: 1

Chapter 13: Network Design and Management
TRUE/FALSE
1.
ANS: T
2.
ANS: F
3.
ANS: T
4.
ANS: T

Computer network technology changes at breakneck speed.
PTS: 1
The systems development life cycle is a one-time only process.
PTS: 1
One very important part of most computer systems today is the network.
PTS: 1
Not all analysis and design projects require all three network connectivity maps.
PTS: 1

5.
In a wide area connectivity map, a dotted line between two sites indicates a desired path for data (or voice) transmission.
ANS: F

PTS: 1

6.
A metropolitan area connectivity map shares some of the characteristics of wide area maps and some of the characteristics of local area maps.
ANS: T

PTS: 1

7.
Latency, delivery rate, and failover are usually significant factors that are included at the local area level.
ANS: F
8.
expensive.
ANS: T

PTS: 1
Analyzing and designing a new computer system can be time-consuming and
PTS: 1

9. projects. ANS: T
10.
benefits.
ANS: F

The term “feasible” has several meanings when it’s applied to computer-based
PTS: 1
When calculating a computer system benefits, you do not need to include intangible
PTS: 1

11.
In a payback analysis, the Development Cost and Operation and Maintenance Costs total the costs of the project over its intended lifetime.
ANS: T

PTS: 1

12.
In a payback analysis, the Cumulative Time-Adjusted Benefits are the Benefits multiplied by the present value of a dollar for each year.
ANS: F

PTS: 1

13.
Computer networks are mission-critical systems, and designing a new computer network or increasing the capacity of a current system requires careful planning.
ANS: T
14.
ANS: F

PTS: 1
Capacity planning is a fairly easy and fast operation.
PTS: 1

15.
Two technologies in computer networking that often generate revenue are wireless
LANs and network security.
ANS: F

PTS: 1

16.
Computer simulations are easy to create, mainly because it is difficult to make mistakes in the modeling process and easy to discover them.
ANS: F

PTS: 1

17.
Compared to simulation, benchmarking is a relatively straightforward technique and can provide useful information when it’s used to analyze a network.
ANS: T
18.
ANS: T
19.
ANS: T

PTS: 1
Setting up a benchmark test can be quite time-consuming.
PTS: 1
Many experts feel analytical modeling is a good way to determine network capacity.
PTS: 1

20.
The advantage of analytical modeling is that it is extremely difficult to create inaccurate analytical models and thus generate results that are invalid.
ANS: F
21.
strengths.
ANS: T

PTS: 1
Once a baseline is created, the results can be used to identify network weaknesses and
PTS: 1

22.
Baseline studies are most effective when they are initiated during a time when the network is experiencing severe problems.
ANS: F

PTS: 1

23.
Collecting information on system users involves determining the maximum number of users, the average number of users, and the peak number of users.
ANS: T

PTS: 1

24.
Assembling information on network applications requires that you create a fairly extensive list of statistics.
ANS: F

PTS: 1

25.
Because shared-segment CSMA/CD networks are contention-based, they do not suffer from collisions.
ANS: F
26.
ANS: T better. 27.

ANS: F
28.
operational.
ANS: T time. 29.

ANS: F
30.
Wireshark.
ANS: T

PTS: 1
It is possible to become certified on a particular type of network operating system.
PTS: 1
Although every device is different, the shorter the mean time between failures, the
PTS: 1
A component or network with a high availability (near 1.0) is almost always
PTS: 1
A reliability of exactly 1.0 means the network or device is reliable 1 percent of the
PTS: 1
A very popular sniffer that can be used on Unix and Windows networks is Ethereal/
PTS: 1

MULTIPLE CHOICE
1.
One of the most popular and successful plans currently used by businesses today is the
____.
a. network cycle
c.
systems development life cycle (SDLC)
b.

software-network cycle

ANS: C

d.

distributed cycle

PTS: 1

2.
In general, a ____ approach is a series of steps and tasks that professionals, such as systems developers, can follow to build high-quality systems faster, with fewer risks, and at lower costs. a.

structured

c.

linear

b.

random

d.

quadratic

ANS: A

PTS: 1

3.
The intent of SDLC is for ____ not to be disjointed steps in a big plan, but overlapping layers of activity.
a.

cycles

c.

rounds

b.

phases

d.

levels

ANS: B
4.

PTS: 1
One technique used to model a corporation’s network environment is to create ____.

a.

link shadows

c.

dots model

b.

node approaches

d.

connectivity maps

ANS: D

PTS: 1

5.
Three different modeling techniques can be used: ____ area connectivity maps, metropolitan area connectivity maps, and local area connectivity maps.
a.

personal

c.

world

b.

wide

d.

universal

ANS: B

PTS: 1

6.
In a wide area connectivity map, mobile or wireless sites are indicated by circles containing the letter ____.
a.

A

c.

M

b.

E

d.

X

ANS: C

PTS: 1

7.
In a wide area connectivity map, external sites, such as suppliers or external agents, are denoted by circles containing the letter ____.

a.

E

c.

M

b.

F

d.

X

ANS: A
8.

PTS: 1
A new parameter that might have an impact on metropolitan area design is the ____.

a.

link shadow

c.

link length

b.

node distance

d.

failover time

ANS: D

PTS: 1

9.
To examine the nodes in a wide area connectivity map in more detail, an analyst can expand each individual site into a ____ area connectivity map.
a.

personal

c.

world

b.

local

d.

universal

ANS: B

PTS: 1

10.
A ____ map can show how individual workstations or groups of workstations are clustered with switches, routers, hubs, and server farms.
a.

local area detailed connectivity c.

metropolitan area connectivity

b.

local area overview connectivity d.

wide area connectivity

ANS: A

PTS: 1

11.
A system’s ____ feasibility is the extent to which the system can be created, given the company’s current finances.
a.

technical

c.

financial

b.

operational

d.

time

ANS: C

PTS: 1

12.
When a company is evaluating a project’s ____ feasibility, the company must ask:
Will the proposed system produce the expected results?
a.

financial

c.

time

b.

technical

d.

operational

ANS: D

PTS: 1

13.
When a company is evaluating a project’s ____ feasibility, the company must ask: Can the proposed system be designed, built, tested, and installed in an amount of time that all parties find reasonable and to which they can agree?
a.

financial

c.

time

b.

technical

d.

operational

ANS: C

PTS: 1

14.
____ analysis is a common financial analysis technique that involves determining a proposed system’s costs and benefits.
a.
Payback
c.
Operational
b.

Time

d.

ANS: A

Technical

PTS: 1

15.
With respect to ____ benefits, the most common measurement is the monthly or annual savings that will result from the use of the proposed system.
a.

intangible

c.

imaginary

b.

tangible

d.

projected

ANS: B

PTS: 1

16.
____ benefits are ones for which assigning a dollar amount is difficult; they include customer goodwill and employee morale.
a.

Tangible

c.

Real

b.

Concrete

d.

Intangible

ANS: D

PTS: 1

17.
When performing a payback analysis calculation, you should show all dollar amounts using the ____.
a.

time value of money

c.

computer simulation

b.

money value of time

d.

benchmarking

ANS: A

PTS: 1

18.
____ means that if something is going to cost one dollar one year from now, you need to put away less than a dollar today to pay for it.
a.

Operational feasibility

c.

Technical feasibility

b.

The money value of time

d.

The time value of money

ANS: D
19.

PTS: 1
In a payback analysis, the ____ Cost is a one-time cost that occurs in Year 0.

a.

Operation and
Maintenance

c.

Time-Adjusted

b.

Development

d.

Cumulative Time-Adjusted

ANS: B

PTS: 1

20.
In a payback analysis, the ____ Costs are simply the running sums of the TimeAdjusted Costs over all the years.
a.

Operation and
Maintenance

c.

Cumulative Time-Adjusted

b.

Development

ANS: C

d.

Time-Adjusted

PTS: 1

21.
In a payback analysis, the ____ values are the running sums of the Time-Adjusted
Benefits over all the years.
a.

Time-Adjusted Benefits

c.

Cumulative Time-Adjusted Costs

b.

Cumulative TimeAdjusted Benefits

d.

Time-Adjusted Costs

ANS: B

PTS: 1

22.
In a payback analysis, the ____ Costs are the Cumulative Time-Adjusted Costs plus the Cumulative Time-Adjusted Benefits for each year.
a.

Time-Adjusted Benefits

c.

Cumulative Lifetime Time-Adjusted

b.

Operation and
Maintenance

d.

Time-Adjusted Costs

ANS: C

PTS: 1

23.
Payback analysis helps you determine the approximate time for a project’s payback, or
____, to occur.
a.

cumulative lifetime

c.

discount factor

b.

benefits derived

d.

return on investment (ROI)

ANS: D

PTS: 1

24.
When a company calculates the ____ for a proposed project, it compares the revenue generated from the project with the expenses incurred.
a.

ROI (return on investment) c.

operational feasibility

b.

technical feasibility

d.

time feasibility

ANS: A

PTS: 1

25.
A number of techniques exist for performing ____ planning, including linear projection, computer simulation, benchmarking, and analytical modeling.
a.

financial

c.

capacity

b.

time

d.

money

ANS: C

PTS: 1

26.
The advantage of using a ____ is that it can mimic conditions that would be extremely difficult, if not impossible, to create on a real network.
a.

computer simulation

c.

time projection

b.

linear projection

d.

benchmark

ANS: A

PTS: 1

27.
____ involves generating system statistics under a controlled environment and then comparing those statistics against known measurements.
a.
Linear projection
c.
Computer simulation
b.

Benchmarking

ANS: B values. 28.

d.

Analytical modeling

PTS: 1
____ involves the creation of mathematical equations to calculate various network

a.

Linear projection

c.

Computer simulation

b.

Benchmarking

d.

Analytical modeling

ANS: D
____.

29.

PTS: 1
One of the best techniques for determining current network capacities is creating a

a.

baseline

c.

return of investment (ROI)

b.

payback analysis

d.

topline

ANS: A

PTS: 1

30.
Network personnel create a ____ to determine the normal and current operating conditions of the network.
a.

linear projection

c.

timeline

b.

computer projection

d.

baseline

ANS: D

PTS: 1

31.
To collect baseline information on ____, you create a list of the number and types of system nodes in the network.
a.

operational protocol

c.

system nodes

b.

system users

d.

network application

ANS: C

PTS: 1

32.
Collecting baseline information on ____ involves listing the types of operational protocols used throughout the system.
a.

system users

c.

network application

b.

operational protocols

d.

system nodes

ANS: B
33.

PTS: 1
Typically, a network reaches saturation when its network utilization is at ____ percent.

a.

55

c.

80

b.

60

d.

100

ANS: D

PTS: 1

34.
To learn new skills and demonstrate proficiency within a particular area, the network administrator can obtain ____.
a.
certification
c.
ROI
b.

policies

d.

ANS: A

capacity planning

PTS: 1

35.
Four statistics, or measures, that are useful in evaluating networks are mean time between failures, mean time to repair, ____, and reliability.
a.

payback

c.

availability

b.

integrity

d.

ROI

ANS: C
36.

PTS: 1
The ____ includes the time needed to bring the system back up to normal operation.

a.

mean time between failures c.

availability

b.

mean time to repair

d.

reliability

ANS: B
37.

PTS: 1
A protocol analyzer is also known as ____.

a.

cable tester

c.

simulator

b.

catcher

d.

sniffer

ANS: D

PTS: 1

38.
____ is an industry standard created by the Internet Engineering Task Force and designed originally to manage Internet components.
a.

Simple Mail Transfer Protocol (SMTP)

b.

Internet Control Message Protocol (ICMP)

c.

Simple Network Management Protocol (SNMP)

d.

Transport Control Protocol (TCP)

ANS: C

PTS: 1

39.
The ____ software controls the operations of a managed element and maintains a database of information about all managed elements.
a.

SNMP agent

c.

SMTP manager

b.

SNMP manager

d.

SMTP agent

ANS: B

PTS: 1

40.
____ is a protocol that allows a network administrator to monitor, analyze, and troubleshoot a group of remotely managed elements.

a.

Remote Network Monitoring (RMON)

b.

Simple Mail Transfer Protocol (SMTP)

c.

Remote Login (rlogin)

d.

File Transfer Protocol (FTP)

ANS: A

PTS: 1

COMPLETION
1.
The ________________________________________ is a structured approach to the development of a business system.
ANS:
systems development life cycle (SDLC) systems development life cycle
SDLC
PTS: 1
2.
A professional called a(n) ____________________ typically is responsible for managing a project and following the SDLC phases.
ANS: systems analyst
PTS: 1
3.
In order to create a(n) ____________________ connectivity map, the modeler begins by identifying each site or location in which the company has an office.
ANS: wide area
PTS: 1
4.
If a company desires a metropolitan area network connection between one of its offices and another business, it can use a(n) ____________________ connectivity map to outline this connection and define the desired network characteristics.
ANS: metropolitan area
PTS: 1
5.
____________________ is the amount of time necessary for the metropolitan area network to reconfigure itself or reroute a packet, should a given link fail.
ANS: Failover time
PTS: 1
6.
If only an overview of a local network is desired, then the analyst can create a(n)
____________________ connectivity map.

ANS: local area overview
PTS: 1
7.
The ____________________ feasibility of a system is the extent to which the system can be created and implemented using currently existing technology.
ANS: technical
PTS: 1
8.
When a system demonstrates ____________________ feasibility, it operates as designed and implemented.
ANS: operational
PTS: 1
9.
A system’s ____________________ feasibility is the extent to which the system can be installed in a timely fashion and meets organizational needs.
ANS: time
PTS: 1
10.
____________________ charts the initial costs and yearly recurring costs of a proposed system against the projected yearly income (benefits) derived from the proposed system.
ANS: Payback analysis
PTS: 1
11.
The ____________________ is a concept that states that one dollar today is worth more than one dollar promised a year from now.
ANS: time value of money
PTS: 1
12.
In a payback analysis, the ____________________ row reflects the total costs for each year times the present value of a dollar for that year.
ANS: Time-Adjusted Costs
PTS: 1
13.
In a payback analysis, the ____________________ values are the benefits, or income amounts, that are expected each year.
ANS: Benefits Derived
PTS: 1

14.
____________________ involves trying to determine the amount of network bandwidth necessary to support an application or a set of applications.
ANS: Capacity planning
PTS: 1
15.
____________________ involves predicting one or more network capacities based on the current network parameters and multiplying those capacities by some constant.
ANS: Linear projection
PTS: 1
16.
A(n) ____________________ involves modeling an existing system or a proposed system using a computer-based simulation tool and subjecting the model to varying degrees of user demand (called load).
ANS: computer simulation
PTS: 1
17.
Creating a(n) ____________________ for an existing computer network involves measuring and recording a network’s state of operation over a given period of time.
ANS: baseline
PTS: 1
18.
___________________________________ is the average time a device or system will operate before it will fail.
ANS:
Mean time between failures (MTBF)
Mean time between failures
MTBF
PTS: 1
19.
______________________________ is the average time necessary to repair a failure within the computer network.
ANS:
Mean time to repair (MTTR)
Mean time to repair
MTTR
PTS: 1
20.
____________________ is the probability that a particular component or system will be available during a fixed time period.

ANS: Availability
PTS: 1
21.
____________________ calculates the probability that a component or system will be operational for the duration of a transaction of time t.
ANS: Reliability
PTS: 1
22.
A(n) ____________________ monitors a network 24 hours a day, seven days a week, and captures and records all transmitted packets.
ANS:
protocol analyzer sniffer PTS: 1
23.
A(n) ______________________________ facilitates the exchange of management information between network devices.
ANS: network management protocol
PTS: 1
24.
running in it.

A managed element has management software, called a(n) ____________________,

ANS: agent
PTS: 1
25.
The database that holds the information about all managed devices is called the
____________________________________.
ANS:
Management Information Base (MIB)
Management Information Base
MIB
PTS: 1
ESSAY
1.

Mention some of the major goals every company has.

ANS:
Every company, whether it’s a for-profit or nonprofit organization, usually has a number of major goals, some of which may include:

* Increasing the company’s customer base
* Keeping customers happy by providing the company’s services as well as possible
* Increasing the company’s profit level, or, in a nonprofit organization, acquiring the funds necessary to meet the organization’s goals and objectives
* Conducting business more efficiently and effectively
From these major goals, systems planners and management personnel within a company try to generate a set of questions that, when satisfactorily answered, will assist their organization in achieving its goals and move the organization forward. For example, someone in management might ask: Is there a way to streamline the order system to allow the company to conduct business more efficiently and effectively? Can we automate the customer renewal system, to better serve customers and keep them happy? Is there a more efficient way to offer new products to help the company increase the customer base? Is there a better way to manage our warehouse system to increase company profits?
PTS: 1
2.

What are the SDLC phases?

ANS:
Although virtually every company that uses SDLC and every textbook that teaches SDLC has its own slightly different variation of the methodology, most agree that the SDLC includes the following phases: * Planning—Identify problems, opportunities, and objectives.
* Analysis—Determine information requirements, analyze system needs, and prepare a written systems proposal.
* Design—Design and build the system recommended at the end of the analysis phase and create the documentation to accompany the system.
* Implementation—Install the system and prepare to move from the old system to the new system; train the users.
* Maintenance—Correct and update the installed system as necessary.
PTS: 1
3.

How do you determine the cost of a system?

ANS:
To determine the cost of a system, it is necessary to include all possible costs. To do this, you will first need to consider all one-time costs such as:
* Personnel costs related to those individuals specifically hired to work on developing the system; these may include the salaries of analysts, designers, programmers, consultants, specialists, operators, secretaries, and so on
* Computer usage costs, which reflect the computing needed to perform the analysis and feasibility studies * Costs of hardware and software for the proposed system
* Costs to train the users, support personnel, and management to use the proposed system
* Supplies, duplication, and furniture costs for the personnel creating the proposed system
But to get a comprehensive understanding of the cost of the system, you must also calculate the recurring costs of the proposed system. These include:
* Lease payments on computer hardware or other equipment
* Recurring license costs for software purchased
* Salaries and wages of personnel who will support the system

* Ongoing supplies that will keep the proposed system working
* Heating, cooling, and electrical costs to support the proposed system
* Planned replacement costs to replace pieces of the system as they fail or become obsolete
PTS: 1
4.

Provide an example of capacity planning using linear projection.

ANS:
For an example of capacity planning—using a linear projection—suppose you work for a company that allows its employees to access the Internet. Informal studies performed in the late 1990s showed that the average Internet user requires a transmission link of 50 kbps. As a precaution, let’s double that figure to 100 kbps to allow room for growth. Additional studies have shown that the peak hour for
Internet access is around 11:00 a.m., at which time about 40 percent of the potential users are on the system. If your system has 1000 potential users, your peak capacity would correspond to 400 concurrent users, each of whom requires a 100-kbps connection. To satisfy this demand, network capacity would need to be 40 Mbps (400 x 100 kbps). Can your local area network support this much traffic? In this example, capacity planning indicates that if your company is not willing to install communications links totaling 40 Mbps, it may have to apply restrictions on how its employees use the
Internet. For example, the company may have to limit the number of simultaneous users or not give the full 100-kbps capacity to each user. Alternatively, the company can simply hope that no more than 40 percent of all its users will access the Internet at the same moment in time.
PTS: 1
5.

What are the skills needed by a network administrator?

ANS:
Because many network administrators are dealing with both computers and people, they need the skills necessary to work with both. A checklist of skills for the network administrator would include a wide platform of technology skills, including, but not limited to, knowledge of local area networks, wide area networks, voice telecommunications systems, data transmission systems, video transmission, basic hardware concepts, and basic software skills. A network administrator should also have interpersonal skills, including the ability to talk to users in order to service problems and explore new applications. Along with interpersonal skills, a network administrator also needs training skills, which involve the ability to train users or other network support personnel.
To make effective use of limited resources, a network administrator should also possess a number of common management skills. For one, the network administrator should have budget management skills, which include knowing how to prepare a budget to justify continuing funds or to request additional funds. Along with those skills, a network administrator needs basic statistical skills, which means that he or she must know how to collect and use system statistics to justify the performance of existing systems or to validate the addition of new ones. Time management skills are also a necessity.
These include the ability to manage not only one’s own time, but also that of projects and any information technology workers who may be working for the administrator. Just as valuable as time management skills are project management skills, which center on the ability to keep a project on schedule and to use project-estimating tools, project-scheduling tools, and other methods for continuous project assessment. Finally, a network administrator should possess policy creation and enforcement skills, which include the ability to create policies concerning the use of the computer systems, access to facilities, password protection, access to applications, access to databases, distribution of hardware and software, replacement of hardware and software, and the handling of service requests.

PTS: 1

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