A proxy server is a computer that acts as an intermediary between the users computer and the Internet. It allows client computers to make indirect network connections to other network services. If use proxy server, client computers will first connect to the proxy server, requesting some resources like web pages, games, videos, mp3, e-books, any other resources which are available from various servers over Internet. As soon as getting such request, the proxy server will seek for the resources from the cache in its local hard disk. If the resources have been cached before, the proxy server will return them to the client computers. If not cached, it will connect to the relevant servers and request the resources on behalf of the client computers. Then it caches resources from the remote servers, and returns subsequent requests for the same content directly
Functions of a proxy server * Help improve web performance by storing a copy of frequently used webpages * Help improve security by filtering out some web content and malicious software * Content filtering * Spying * To keep machines behind it anonymous (mainly for security). * To speed up access to resources (using caching). Web proxies are commonly used to cache web pages from a web server. * To apply access policy to network services or content, e.g. to block undesired sites. * To log / audit usage, i.e. to provide company employee Internet usage reporting. * To bypass security/ parental controls. * To scan transmitted content for malware before delivery. * To scan outbound content, e.g., for data leak protection. * To circumvent regional restrictions.
2. What are the functions of a Simple Network Management Protocol (SNMP) agent.
The SNMP extension agent functions define the interface between the SNMP service and the third-party SNMP extension agent DLLs. * Requests that the SNMP extension agent deallocate resources and terminate operations. * Identifies any additional management information base (MIB) subtrees that the SNMP extension agent supports. * Provides the SNMP extension agent with information about the internal counters and parameters of the service. * Processes SNMP requests that specify variables in one or more MIB subtrees that are registered by SNMP extension agents. * Retrieves information that the service requires to generate traps for the SNMP extension agent.
3.Name and explain three main components of extensible authentication protocol 1. Supplicant (client software) 2. Authenticator (access point) 3. Authentication Server (a RADIUS/AAA server

Supplicant(client server )- supplicant is an entity at one end of a point-to-point LAN segment that seeks to be authenticated by an authenticator attached to the other end of that link.

Authenticator(access point)- An authenticator is a way to prove to a computer system that you really are who you are (called authentication). It is either: A piece of data (often called a token) that you got from the last place where you proved who you are (to save you, or the software, the hassle of logging in again).
Authentication Server (a RADIUS/AAA server)- An authentication server is an application that facilitates authentication of an entity that attempts to access a network. Such an entity may be a human user or another server. An authentication server can reside in a dedicated computer, an Ethernet switch, an access point or a network access server.
What are the roles of bandwidth shapers in a network.?
Bandwidth shapers manipulate, manage and control the network connections to the outside world and they determine allowed bandwidth consumption based on the types of activities. They are more like internet service providers.
What is encryption?
Encryption is the conversion of electronic data into another form, called ciphertext, which cannot be easily understood by anyone except authorized parties.
What is the difference between delay and jitter?
Delay: Is the amount of time data(signal) takes to reach the destination. Now a higher delay generally means congestion of some sort of breaking of the communication link.
Jitter: Is the variation of delay time. This happens when a system is not in deterministic state eg. Video Streaming suffers from jitter a lot because the size of data transferred is quite large and hence no way of saying how long it might take to transfer.
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