What is a CAM table and why is it important for switching performance?

• A. CAM maps IP addresses to switch ports.
• B. CAM is a memory used by routers to store routing tables.
• C. CAM stores VLAN membership for devices.
• D. CAM maps MAC addresses to switch ports; learning enables efficient forwarding; overflow leads to flooding.

Answer: (D)

CAM tables map MAC addresses to the switch ports where those devices are reachable, and they’re built through learning. When a frame arrives, the switch records the source MAC and the ingress port in the CAM. This lets the switch remember which port to use for that MAC in future frames, so it can forward traffic directly to the correct destination without sending it everywhere.

This hardware-based lookup is central to switching performance because it enables fast, exact-match decisions on where to forward frames (often in constant time). If a frame is addressed to a MAC that isn’t in the CAM, or if the CAM is full, the switch can’t find a specific destination port and must flood the frame to all ports in the VLAN. Flooding creates unnecessary traffic and reduces performance, highlighting why keeping the CAM populated with fresh, accurate entries is important.