Which statement best describes switch behavior in a LAN?

Which statement best describes switch behavior in a LAN?

• A. It uses IP addresses to forward frames
• B. It uses MAC addresses to forward frames to the correct port
• C. It uses DNS names to route data
• D. It uses NNTP to deliver data

Answer: (B)

Switches operate at Layer 2 and make forwarding decisions based on MAC addresses. When a frame arrives, the switch learns the source MAC and the port it came from, building a MAC address table. If the destination MAC is known, the switch forwards the frame only to the port tied to that MAC, which prevents unnecessary traffic on other ports. If the destination MAC hasn’t been seen yet, the switch floods the frame to all ports in the same VLAN to find the destination. This MAC-based forwarding is what makes a LAN switch efficient. Using IP addresses would be the job of a router, not a switch, since IP is Layer 3 routing. DNS names are for name resolution, not for forwarding at the data-link layer, and NNTP is a news protocol, unrelated to switch forwarding.

Switches operate at Layer 2 and make forwarding decisions based on MAC addresses. When a frame arrives, the switch learns the source MAC and the port it came from, building a MAC address table. If the destination MAC is known, the switch forwards the frame only to the port tied to that MAC, which prevents unnecessary traffic on other ports. If the destination MAC hasn’t been seen yet, the switch floods the frame to all ports in the same VLAN to find the destination. This MAC-based forwarding is what makes a LAN switch efficient.

Using IP addresses would be the job of a router, not a switch, since IP is Layer 3 routing. DNS names are for name resolution, not for forwarding at the data-link layer, and NNTP is a news protocol, unrelated to switch forwarding.