Internet Addressing Scheme

By Pauline M. Berry

For the Internet to be a world-wide open communication system it was necessary to develop a way of identifying computers. So each host on the internet is assigned a unique 32-bit Internet address: the IP address. The IP address contains four fields, each separated by a dot. Each field is decimal and specify 8 bits if the address. Also, there are 3 classes of address, depending on how much of the IP address goes to specify the network portion and how much the local portion.

Class A: There can only exist 126 class A networks each of which can support 16,77,214 hosts

Class B: This is used for large networks such as campus networks and WANs. There can be 64 x 254 class B Networks each with a maximum of 65 532 hosts. There is also a reserved number for broadcasting. For example, the Strathclyde University Network has a class B address so that some sample hosts addresses at Strathclyde look like:

Class C: Most commonly assigned to LANs but only allows 254 hosts on each network. However, one site may have 2 class C addresses assigned to it.

This class system was designed before the rapid growth in internet use and a new addressing scheme will have to be developed.
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