Network Classes

Class A uses the first octet for the network address, and the rest for host addresses within this network. For example, a site whose network address is 129.0.0.0 would own the 2²⁴ addresses between 129.0.0.0 and 129.255.255.255.

Class B uses two octets for the network address, and two for the host address. For example, a site whose network address is 129.123.0.0 would own the 2¹⁶ addresses between 129.123.0.0 and 129.123.255.255.

Class C uses three octets for the network address, and one octet for the host address. For example, a site whose network address is 129.123.56.0 would own the 2⁸ addresses between 129.123.56.0 and 129.123.56.255.