Class Leftmost bits Start address Finish address
A 0xxx
B 10xx
C 110x
D 1110
E 1111

IP Address Class D and Multicast

The IPv4 networking standard defines Class D addresses as reserved for multicast. Multicast is a mechanism for defining groups of nodes and sending IP messages to that group rather than to every node on the LAN (broadcast) or just one other node (unicast).

Multicast is mainly used on research networks. As with Class E, Class D addresses should not be used by ordinary nodes on the Internet.

IP Address Class E and Limited Broadcast

The IPv4 networking standard defines Class E addresses as reserved, meaning that they should not be used on IP networks. Some research organizations use Class E addresses for experimental purposes. However, nodes that try to use these addresses on the Internet will be unable to communicate properly.

A special type of IP address is the limited broadcast address A broadcast involves delivering a message from one sender to many recipients. Senders direct an IP broadcast to to indicate all other nodes on the local network (LAN) should pick up that message. This broadcast is 'limited' in that it does not reach every node on the Internet, only nodes on the LAN.

Technically, IP reserves the entire range of addresses from through for broadcast, and this range should not be considered part of the normal Class E range.