Internet Protocol Tutorial
Classes of IP Addresses, IP Broadcast and IP Multicast


IPv4 Address Classes
The IPv4 address space can be subdivided into 5 classes - Class A, B, C, D and E. Each class consists of a contiguous subset of the overall IPv4 address range.

The values of the leftmost four bits of an IPv4 address determine its class as follows:

All Class C addresses, for example, have the leftmost three bits set to '110', but

All Class C addresses, for example, have the leftmost three bits set to '110', but each of the remaining 29 bits may be set to either '0' or '1' independently (as represented by an x in these bit positions):

110xxxxx xxxxxxxx xxxxxxxx xxxxxxxx Converting the above to dotted decimal notation, it follows that all Class C addresses fall in the range from 192.0.0.0 through 223.255.255.255.