What kind of domains do routers create

A broadcast domain contains all devices that can reach each other at the data link layer OSI layer 2 by using broadcast. All ports on a hub or a switch are by default in the same broadcast domain. In the picture above we have three broadcast domains, since all ports on a hub or a switch are in the same broadcast domain, and all ports on a router are in a different broadcast domain.

About twenty years ago, having a network with a lot of devices could impact your performance because of broadcast traffic. Older operating systems also used a lot of broadcast traffic for their applications. How do we create multiple broadcast domains? One way to do this is by adding a router to your network:. How many broadcast domains and collision domains are on a basic port switch using half-duplex mode? More, do you know why the correct answer is correct and the incorrect answers are incorrect?

The answer and explanation is available at the end of this post. With a basic understanding of how switches and routers work, you can add three additional network terms: segment, broadcast domain, and collision domain. Sign up for the free Networking Components course here. The following figure shows a network with a hub, a router, and a switch. You can see how the hub creates a single logical connection between computers A, B, and C, and the router.

This logical connection is a segment. In contrast, the switch in Network 2 isolates the connections between the router, and computers D, E, and F. The connection between Computer D and the switch is one segment, the connection between Computer E and the switch is another segment, and so on. Network 1 is both a collision domain and a broadcast domain. If computer A sends unicast traffic, it can collide with unicast traffic sent by Computer B, Computer C, or the router.

Because of this, the segment created by the hub is a collision domain. In the picture above we have a network of six computers, two hubs, a bridge, a switch, and a router. The broadcast domains are marked in red. Remember, all devices connected to a hub, a bridge, and a switch are in the same broadcast domain. Only routers separate the LAN into multiple broadcast domains.