In IPv4 address, we have 5 classes namely Class A, Class B, Class C, Class D and Class E

but only 3 are usable i.e. Class A, Class B and Class C

Class A

This class of IP Address is used for a network with large number of computers, most used by Large scale business

It has a subnet mask of 255.0.0.0, which means that the first octet represent the Network ID whiles the 2nd, 3rd and 4th octet represents the Host ID, so therefore is divided into two.

255.0.0.0
NIDHID

 

Class B

This class of IP Address is used for a network with medium number of computers, most used by medium scale business

It has a subnet mask of 255.255.0.0, which means that the 1st and 2nd octet represent the Network ID whiles the 3rd and 4th octet represents the Host ID, so therefore is divided into two.

 

255.255.0.0
NIDHID

 

 

Class C

This class of IP Address is used for a network with small number of computers, most used by small scale business

It has a subnet mask of 255.255.255.0, which means that the 1st, 2nd and 3rd octet represent the Network ID whiles the 4th octet represents the Host ID, so therefore is divided into two.

255.255.255.0
NIDHID

 

 

Class D

This class is mostly used for Multicasting by computer services or protocols

 

Class E

This class is mostly used for research and experiment