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IP addresses are divided into three classes, class A, class B and class C. The rest of the IP
addresses are for multicast and broadcast. The bit length of the network prefix is the same as that of the
subnet mask and is denoted as IP address/X, for example, 192.168.1.0/24. Each class has its address
range described below.
Class A:
Address is less than 126.255.255.255. There are a total of 126 networks can be defined because
the address 0.0.0.0 is reserved for default route and 127.0.0.0/8 is reserved for loopback function.
0
Class B:
IP address range between 128.0.0.0 and 191.255.255.255. Each class B network has a 16-bit
network prefix followed 16-bit host address. There are 16,384 (2^14)/16 networks able to be defined with
a maximum of 65534 (2^16 –2) hosts per network.
10
Class C:
IP address range between 192.0.0.0 and 223.255.255.255. Each class C network has a 24-bit
network prefix followed 8-bit host address. There are 2,097,152 (2^21)/24 networks able to be defined
with a maximum of 254 (2^8 –2) hosts per network.
110
Bit # 0 1 7 8 31
Network address Host address
Bit # 01 2 15 16 31
Network address Host address
Bit # 0 1 2 3 23 24 31
Network address Host address