Class a address. The first bit of class A address must be 0, the first eight bits (one byte) represent the network number, and the last 24 bits (three bytes) represent the host number. So the address range is from 1.0.0 to 127.255. Class b address. The first two digits of Class B address must be 10, the first 16 (2 bytes) represents the network number, and the last 16 (2 bytes) represents the host number. So its address range is from 128.0.0 to 19 1.

Class c address. The first three digits of Class C address must be 1 10, the first 24 digits are the network number, and the last 8 digits are the host number. Its address ranges from 192.0.0.0 to 223.255.255.25. Class d addresses are usually used for multicast addresses. It starts with 1 1 10, and the rest are multicast addresses. Multicast addresses are suitable for a specific class of hosts: the multicast addresses of hosts in the same group are the same. Class E addresses begin with1110, which is a reserved address and not widely used in practice.