8 bits 8 bits 8 bits 8 bits
Network Host Host Host
Class A
8 bits 8 bits 8 bits 8 bits
Network Network Host Host
Class B
8 bits 8 bits 8 bits 8 bits
Network Network Network Host
Class C
0
01
011
Binary network address starts with “0”, so the first byte can be between 1 and 127 (decimal).
The first byte identifies the network and the remaining three bytes identify the host.
Example: 104.122.245.10 (where “104” identifies the network and “122.245.10” the host),
Number of possible networks: 127,
Max. number of hosts: 16777214.
Binary network address starts with “10”, so the first byte can be between 128 and 191 (decimal).
The first two bytes identify the network and the remaining two bytes identify the host.
Example: 155.113.16.102 (where “155.113” identifies the network and “16.102” the host),
Number of possible networks: 16384,
Max. number of hosts: 65534.
Binary network address starts with “110”, so the first byte can be between 192 and 223 (decimal).
The first three bytes identify the network and the remaining byte identifies the host.
Example: 210.222.126.55 (where “210.222.126” identifies the network and “55” the host),
Number of possible networks: 2097152,
Max. number of hosts: 254.
Note: Although 256 host addresses should be theoretically possible in this example, the addresses
0 (0b00000000 in binary) and 255 (0b11111111 in binary) are reserved.
Figure 1-4: Overview of IP address classes