What happens in a CAM table overflow?

• A. Switch learned too many MACs; causes flooding and performance issues.
• B. Switch runs out of memory for routes.
• C. VLANs are dropped.
• D. IP addresses collide.

Answer: (A)

CAM table overflow happens when the switch’s MAC address table fills up with learned MACs, leaving no room for new entries. When that happens, the switch can’t map a MAC address to a specific port, so it floods unknown unicast frames to all ports in the VLAN to ensure delivery. That flooding increases traffic on every port, degrades performance, and can raise CPU load as the device handles more frames and MAC aging decisions. In data centers, this is a classic symptom of MAC flooding and the root cause of performance issues because normal switching decisions break down and frames are broadcast more than necessary.

The other scenarios aren’t what CAM table overflow describes: it isn’t about running out of memory for routing tables, it doesn’t cause VLANs to be dropped, and it isn’t about IP address collisions.