Class Address Ranges

Class A - 1.0.0.0 to 126.0.0.0
Class B - 128.0.0.0 to 191.255.0.0
Class C - 192.0.1.0 to 223.255.255.0

Class D* - 224.0.0.0 to 239.255.255.255
Class E* - 240.0.0.0 to 255.255.255.255

Class A, Class B, and Class C are the three classes of addresses used on IP networks in common practice. Class D addresses are reserved for multicast. Class E addresses are simply reserved, meaning they should not be used on IP networks (used on a limited basis by some research organizations for experimental purposes).

Reserved Address Ranges

Address ranges below are reserved by IANA for private intranets, and not routable to the Internet. For additional information, see RFC 1918.

10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

Other reserved addresses:

127.0.0.0 is reserved for loopback and IPC on the localhost.
224.0.0.0 - 239.255.255.255 is reserved for multicast addresses.
255.255.255.255 is the limited broadcast address (limited to all other nodes on the LAN)