What device segments a broadcast domain?

A router is indeed the device that segments a broadcast domain. In a network, a broadcast domain is defined as the set of all devices that can receive broadcast frames originating from any device within that set. Routers operate at Layer 3 of the OSI model and are specifically designed to route traffic between different networks. They effectively filter and manage traffic, preventing broadcast packets from one network segment from reaching others. This means that each interface on a router represents a separate broadcast domain, and routers are essential for controlling traffic between these domains to enhance network performance and security.

Switches, hubs, and repeaters all operate at different layers and functions within a network. For instance, switches can segment collision domains but do not inherently segment broadcast domains unless they are managed or layer 3 switches. Hubs and repeaters simply extend the network by amplifying signals but do not modify or filter traffic, allowing all traffic to be broadcasted to all devices in the network. Thus, while these devices play important roles in network design, they do not serve the specific function of segmenting broadcast domains like a router does.