Which of the following devices would you use to separate broadcast domains on a network?

Which of the following devices would you use to separate broadcast domains on a network?

• Switch
• Router
• Hub
• Bridge 

EXPLANATION

A switch uses layer two of the OSI model, so the switch uses MAC addresses to send frames to the correct device. Rather than sending it to all ports a switch only sends the frame out one port, if it has the MAC address in its MAC address table. If not the switch will send the frame on all ports except for the port in which the frame was received on. Switches provide separate collision domains on each port, this provides dedicated bandwidth to that device and allows simultaneous conversations between devices on different ports. Each port can be operated at full-duplex so the device can send and receive information at the same time.  

A broadcast domain is like a collision domain, however the difference is these broadcast domains belong to a set of devices in the same layer two domain. These kind of blur together between a layer three broadcast message and a layer two broadcast message (FFFF:FFFF:FFFF). A layer two broadcast goes to every host in the same LAN/VLAN. To make it little more fun there are two types of layer three broadcast messages
Limited/Local Broadcast – (255.255.255.255) is often used when the host really has no idea what network its on and waits for a DHCP server to respond back. As well as if a host needs to know the MAC address of a another host on the same LAN/VLAN. This broadcast goes to every host on the same LAN/VLAN and is the most common type of broadcast message.
Directed Broadcast – Is a directed IP packet whose destination is a valid broadcast address on the network that the host is not currently a part of. A router would forward this on to the correct network, however this is usually disabled by default. Example 192.168.1.255/24
Also keep in mind when you send a layer three broadcast you’ll also send a layer two broadcast regardless of what type of layer three broadcast message is sent. This also works the other way, when you send a layer two broadcast message you’ll also send a layer three broadcast message.