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Networking Fundamentals · Foundational

Broadcast

One-to-all communication in which a single frame or packet is delivered to every host on the local segment.

Definition

Broadcasts are used by ARP requests, DHCP discovery and some legacy protocols. Switches flood broadcasts out all ports in the VLAN, while routers stop them. Excessive broadcasts consume bandwidth and CPU, which is one reason to segment large networks. IPv6 has no broadcast.

Example

An ARP request asking "who has 192.168.1.1?" is sent as a broadcast.

Exam tip

Routers separate broadcast domains; switches (without VLANs) do not.

Don't confuse it with

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