Understanding Ethernet Collision Domains

C

An Ethernet collision domain refers to a segment of a network where a collision can occur. A collision happens when two or more devices transmit data simultaneously, resulting in data loss or corruption. The collision domain is a critical consideration when designing or troubleshooting Ethernet networks.

The correct answer to the question is:

C. If a switch is used, the collision domain is limited to each device and the switch.

Explanation: Ethernet hubs, switches, bridges, and routers are all devices that can be used to connect devices in an Ethernet network. Each of these devices works differently and has a different impact on the collision domain.

• Hubs: A hub is a device that connects multiple devices in a network. When a device sends data to the hub, the hub broadcasts the data to all the other devices in the network. This means that all devices connected to a hub are in the same collision domain, and collisions can occur between any of them. Answer B is incorrect because the collision domain is not limited to each device and the hub but includes all devices connected to the hub.

• Switches: A switch is a device that connects multiple devices in a network and learns the MAC addresses of the devices connected to its ports. When a device sends data to the switch, the switch forwards the data only to the destination device. This means that each device connected to a switch is in a separate collision domain, and collisions can only occur between a device and the switch. Answer C is correct because the collision domain is limited to each device and the switch.

• Bridges: A bridge is a device that connects two or more network segments and learns the MAC addresses of the devices connected to its ports. When a device sends data to the bridge, the bridge forwards the data only to the segment where the destination device is located. This means that all devices connected to a bridge are in the same collision domain, and collisions can occur between any of them. Answer D is incorrect because the collision domain includes all devices connected to the bridge.

• Routers: A router is a device that connects multiple networks and forwards data between them. When a device sends data to a router, the router forwards the data to the destination network. This means that all devices connected to a router are in different collision domains, and collisions can only occur between a device and the router. Answer A is incorrect because the collision domain is not limited to all devices connected to the router but only to a device and the router.

In summary, switches are the best devices to reduce the collision domain in Ethernet networks. By limiting the collision domain to each device and the switch, switches can improve network performance and reduce data loss or corruption.