The Actual Class A, B, and C Network Numbers

The Actual Class A, B, and C Network Numbers

The previous example included three networks: Class A network 8.0.0.0, Class B network 130.4.0.0, and Class C network 199.1.1.0. There are other Class A, B, and C networks, however.

The different Class A, B, and C network numbers do not overlap in order to prevent address duplication. If TCP/IP allowed a Class A network 8.0.0.0 and a Class B network 8.1.0.0, IP address 8.1.1.1 would appear to be in both networks, which would cause a lot of confusion. Likewise, if some house on the other side of town had the same mailing address as yours, the postal service would probably get confused.

To avoid such confusion, IP defines a range of Class A, B, and C network numbers. Table 10-2 summarizes the network numbers, the total number of each type, and the number of hosts in each Class A, B, and C network.