A B and C Classes of Networks

The A, B, and C classes of networks are different IP address classes that were defined in the original version of the Internet Protocol (IPv4).

Each class of network is identified by the first few bits of the IP address, which are known as the address class. The address class determines how many bits are used to represent the network portion of the address, and how many bits are used to represent the host portion.

Here is a brief overview of the three classes:

Class A networks use the first octet (the first 8 bits) to identify the network, and the remaining three octets to identify hosts on that network. The first bit of the first octet is always 0, which leaves 7 bits to represent the network. This means that there can be a total of 128 Class A networks, each of which can have up to 16,777,214 hosts.

Class B networks use the first two octets (the first 16 bits) to identify the network, and the remaining two octets to identify hosts on that network. The first two bits of the first octet are always 10, which leaves 14 bits to represent the network. This means that there can be a total of 16,384 Class B networks, each of which can have up to 65,534 hosts.

Class C networks use the first three octets (the first 24 bits) to identify the network, and the remaining octet to identify hosts on that network. The first three bits of the first octet are always 110, which leaves 21 bits to represent the network. This means that there can be a total of 2,097,152 Class C networks, each of which can have up to 254 hosts.

Each class of network has its own default subnet mask, which is used to determine which bits of the IP address represent the network portion and which represent the host portion. The subnet mask is used in conjunction with the IP address to determine whether a destination address is on the same network or a different network, and to calculate the appropriate routing information.