Knowledge Base: : Broadcast Address

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Broadcast Address
By nsutriana

In computer networking, a broadcast address is an IP address that allows information to be sent to all machines on a given subnet rather than a specific machine. The exact notation can vary by operating system, but the standard is laid out in RFC 919.

Generally, the broadcast address is found by taking the bit complement of the subnet mask and then OR-ing it bitwise with the IP address.

Example: to broadcast a packet to an entire class B subnet using a private IP address space, the broadcast address would be 172.16.255.255.

This can be found from the subnet mask (255.255.0.0) and the IP address (eg. 172.16.48.196) - the complement of the subnet mask is 0.0.255.255, and 172.16.48.196 | 0.0.255.255 = 172.16.255.255.

A special type of IP address is the limited broadcast address 255.255.255.255. A broadcast involves delivering a message from one sender to many recipients. This broadcast is 'limited' in that it does not reach every node on the Internet, only nodes on the LAN.

http://en.wikipedia.org/wiki/Broadcast_address

Article added 07/14/07.