Which device forwards frames within a local network using MAC addresses?

• A. Directs frames within a LAN using MAC addresses
• B. Routes traffic between networks
• C. Protects a network by filtering traffic
• D. Converts IP addresses to hostnames

Answer: (A)

The key idea is how devices move frames inside a local network using MAC addresses. A switch does this by building a MAC address table that links each device’s MAC address to the switch port it’s seen on. When a frame arrives, the switch looks up the destination MAC and forwards the frame only to the port where that device is reachable. If the destination isn’t known yet, the switch floods the frame to all ports except the source, and once the destination responds, it learns where that MAC is located. This keeps traffic contained within the local network and makes communication efficient by avoiding unnecessary broadcasts.

Other devices aren’t doing this in the same way: a router routes between networks using IP addresses, a firewall filters traffic for security, and DNS maps domain names to IP addresses rather than forwarding frames based on MAC addresses.