What does a layer 2 switch use to direct packets?

A layer 2 switch uses the MAC address to direct packets within a local area network (LAN). MAC addresses are unique identifiers assigned to network interfaces for communications on the physical network segment. When a layer 2 switch receives a data packet, it examines the destination MAC address contained in the packet's header. The switch then looks up this address in its MAC address table, which maps each MAC address to the port on which it was last seen.

By using this method, the switch can make intelligent forwarding decisions, sending the packet only to the appropriate port rather than broadcasting it to all ports. This helps in reducing unnecessary traffic on the network and improves overall network efficiency.

Other choices do not apply to the operation of a layer 2 switch. The IP address is relevant at layer 3 (the Network layer) for routing, the subnet mask assists in defining network boundaries and is also related to layer 3, while the port number is used in transport layer protocols, such as TCP/UDP, for distinguishing between different services or applications running on a device.