From time to time, a device on the network will
want to communicate with all other “local” devices
at the same time. Typically, this occurs when a
device wants to query the network for an IP address,
when a device is newly added to a network, or when
a change occurs in the network.
A group of devices that receive all broadcast messages
from members of that group is called a
broadcast domain. Network broadcast domains
typically are segmented with Layer 3 devices (routers).
Think of a broadcast domain as like standing in
your yard and yelling as loudly as you can. The
neighbors who hear you are within your broadcast
domain.