IP Addressing:
Who’s Got Class and Who’s Special
Chelley Cline
NT2640

We live in a time of marvel and discovery. We have phones and computers in our pockets and in our cars. Our workplaces expect us to use equipment that literally can talk to the world. These things are so much a part of our lives that we forget they are the result of years of development and standardizing. The wonders of that result are far overshadowed by the systems that enable them to work. At the most basic level the internet is like a huge mail delivery system. While that is a vast simplification, it gives a framework to understand why and how some of the fundamental rules came into play. Originally there were just 32-bit numbers as IP addresses – no classes or obvious distinction between network and host bits. It was assumed that the first eight bits were the network. This only offered 254 networks. Many organizations didn’t need 16,777,214 host addresses, and over time it was obvious that we needed not only different sizes of networks, but more of them. In 1981 a new way to partition the bits of an IP address was put into use. In order to be able to easily see which bits were network and which were host, a class system was defined. (Sharma, 2011) The IANA has set rules that are followed worldwide to allow international use of the internet and intranets. Using the knowledge that an octet can only show numbers between zero and 255, classes were developed for the numbers that designate a network, which has nodes - or devices - within it. Class A networks are ones that the first octet starts with binary digit zero, so 00000001 to 01111111 or 1 to 127. It is accepted that 127.0.0.0 is not used as an IP network. It is only used within your computer, often as a loopback address to ascertain whether TCP/IP is properly installed and functional. As part of the definition of a