Address Class

Class 1 2 3 4 5 6-8 9-16 17-24 25-32
A 0 Network ID Host ID
B 1 0 Network ID Host ID
C 1 1 0 Network Id Host ID
D 1 1 1 0 Multicast Address
E 1 1 1 1 0 Reserved

Class E is reserved for IAB, so we can not use.

Network ID

ID that represents local network.

Host ID

ID that represents one host.

Number of addresses

Class Network Host
A 126 16,777,214
B 16,382 65,534
C 2,097,150 254

Address Meaning

Network ID Host ID  
0 0 Used when emitting host doesn’t know own address for bootstrap, etc. Special use.
0 Host Number Network
Network Number 1 for all Broadcast for the network
127 Whatever For loopback test