What is a CAM table in a switch, and what happens when a switch learns a new MAC address?

• A. The CAM table maps MAC addresses to switch ports; learning records the association to forward frames directly.
• B. The CAM table stores VLAN IDs for each port; learning updates VLAN assignments.
• C. The CAM table maps IP addresses to switch ports; learning updates routing information.
• D. The CAM table stores routing information for inter-VLAN routing.

Answer: (A)

A switch uses a CAM table to map MAC addresses to the switch port where that device was observed. When a frame arrives, the switch records the source MAC and the ingress port in the CAM table. This learning lets future frames destined for that MAC be forwarded directly out the learned port, rather than being flooded to all ports. If the destination MAC isn’t in the CAM table, the switch floods the frame to all ports in the same VLAN to reach it. Entries in the CAM table typically age out after a timeout so the table stays current.

Other concepts like storing VLAN IDs or IP routing information are not handled by the CAM table. VLAN IDs belong to VLAN configuration, and IP routing tables are used for Layer 3 paths, not for learning MAC-to-port associations used for switching.