Which component forwards frames based on MAC addresses within a LAN?

Which component forwards frames based on MAC addresses within a LAN?

• A. Router
• B. Hub
• C. Switch
• D. Firewall

Answer: (C)

Frames are forwarded on a LAN by a switch using MAC addresses. A switch builds and maintains a MAC address table that maps each device’s hardware address to the port it’s reachable on. As frames arrive, the switch notes the source MAC and the port it came from, updating the table. When a frame finally has a destination MAC, the switch looks up that address and forwards the frame only to the specific port associated with that MAC, not to every port. If the destination MAC isn’t yet known, the switch floods the frame to all ports to learn where the device is. This selective forwarding keeps traffic localized to the right segment and reduces collisions, which is essential for efficient LAN operation and supports per-port segmentation. A router, in contrast, makes forwarding decisions based on IP addresses and moves traffic between different networks. A hub simply repeats every incoming frame to all other ports, with no MAC learning or selective forwarding. A firewall focuses on inspecting and filtering traffic based on security rules, typically between networks, and doesn’t perform MAC-based forwarding within a LAN.

Frames are forwarded on a LAN by a switch using MAC addresses. A switch builds and maintains a MAC address table that maps each device’s hardware address to the port it’s reachable on. As frames arrive, the switch notes the source MAC and the port it came from, updating the table. When a frame finally has a destination MAC, the switch looks up that address and forwards the frame only to the specific port associated with that MAC, not to every port. If the destination MAC isn’t yet known, the switch floods the frame to all ports to learn where the device is. This selective forwarding keeps traffic localized to the right segment and reduces collisions, which is essential for efficient LAN operation and supports per-port segmentation.

A router, in contrast, makes forwarding decisions based on IP addresses and moves traffic between different networks. A hub simply repeats every incoming frame to all other ports, with no MAC learning or selective forwarding. A firewall focuses on inspecting and filtering traffic based on security rules, typically between networks, and doesn’t perform MAC-based forwarding within a LAN.