What does a switch do when it receives a frame addressed to a MAC that is not in its CAM table?

• A. Drops the frame.
• B. Forwards only to the gateway.
• C. Floods the frame out all ports in the same VLAN except the source port.
• D. Rewrites the destination MAC to broadcast.

Answer: (C)

A switch uses a CAM table to map MAC addresses to the port where that device is reachable. When a frame arrives, it checks the destination MAC. If that MAC is already in the CAM table, the switch forwards the frame only to the port listed for that MAC (within the same VLAN). If the destination MAC isn’t in the CAM table, the switch doesn’t know where the device is, so it floods the frame out all ports in the same VLAN except the port it arrived on. This ensures the frame has a chance to reach the destination, and the switch will learn the source MAC and its port for future frames. The flooding is limited to the VLAN and isn’t sent to the gateway, and the switch doesn’t rewrite the destination to broadcast.