When the RFC was written, developers had a concept to subdivide IP into five classes or formats of addresses. IPv4 addresses are divided into classes A-E, as shown here:
|
Class |
Range |
Use |
|
A |
0.0.0.0 to 127.255.255.255 |
Assignable (to companies) |
|
B |
128.0.0.0 to 191.255.255.255 |
Assignable (to companies) |
|
C |
192.0.0.0 to 223.255.255.255 |
Assignable (to companies) |
|
D |
224.0.0.0 to 239.255.255.255 |
Multicast |
|
E |
240.0.0.0 to 255.255.255.255 |
Experimental |
Classes of IPv4 addresses
As outlined, classes A, B, and C are assigned mainly to companies. Class D is for multicast only, and class E is experimental, and not used.
IPv4 has several ranges of special and private IPv4 addresses, as outlined next.