Broadcast Domain: A set of all devices that recieve broadcast frames originating from any device within the set. Broadcast domains are typically bounded by routers (or, in a switched network, by VLANs) because routers do not forward broadcast frames.Collision Domain: In Ethernet, the network area within which frames that have collided are propagated. Repeaters and Hubs prpagate collisions, LAN switches and bridges do not.