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Broadcast domain

Broadcast domain definition

A broadcast domain is a network segment in which, if one device sends a broadcast message, all other devices in that segment will receive it.

See also: network layer, collision domain, subnetting, address resolution protocol cache

How a broadcast domain works

Devices in a network sometimes send messages to communicate to all other devices in the same network segment. These messages are called broadcasts, and the segment is called a broadcast domain. Every device within one broadcast domain receives these messages.

While switches and hubs send the broadcast messages within the domain, routers limit their scope. They don't forward the messages beyond their specific area, preventing them from flooding the entire network.

Understanding broadcast domains helps network professionals fix network issues or improve infrastructure.

Broadcast domain use cases

  • Local area networks (LANs). Devices within the same LAN often share the same broadcast domain.
  • Virtual local area networks (VLANs). These are segments of a network made to break up larger areas for better control and safety. Each VLAN acts as its own broadcast domain.
  • Ethernet networks. In wired connections using Ethernet, when a device sends a broadcast, all devices in that Ethernet segment receive it.
  • Wireless networks. In Wi-Fi networks, devices connected to the same access point are usually in the same broadcast domain.