A CAM table (Content Addressable Memory table) is the list a switch keeps that maps MAC addresses to the ports and VLANs where it last saw them. The switch learns this by reading the source MAC on each frame and noting ‘this address is on this port’. When a new frame arrives, the switch looks up the destination MAC. If it finds a match, it sends the frame only to that port. If it does not, it floods the frame to all ports in that VLAN so the right device can respond and be learned. Entries age out after a short timer unless fresh traffic refreshes them. Admins can also add static entries that do not age. The table has a fixed size, so if it fills up the switch floods more traffic. Attacks like MAC flooding exploit this, which is why features such as port security exist.
