Collision Domains and Broadcast Domains

In computer networking, a collision domain is a network segment where packets can collide with one another when sent at the same time. In Ethernet networking, a collision domain is a single shared channel through which multiple devices communicate. When two devices transmit at the same time, a collision occurs and both devices must retransmit their packets.

A broadcast domain is a logical division of a computer network, in which all devices can reach each other by broadcast at the data link layer. In other words, a broadcast domain is a network segment that is connected by a shared medium or a switch and can receive broadcast traffic sent by any device within the same segment. Devices in different broadcast domains require a router or layer 3 switch to communicate with each other.