MAC address table
The switch's table of which MAC address is behind which port. It's the basis for all switching: the switch learns the addresses by looking at incoming frames and uses the table to forward traffic only to the right port.
Mechanic: when a frame comes in, the switch notes the sender's MAC + the ingress port in the table ("learning"). When it needs to send a frame it looks up the destination MAC: if it's in the table → send out only on that port; if it's not → flood all ports until the reply reveals where it sits. Entries age out (aging, typically 5 min) if not seen. This is what makes a switch smarter than a hub (which blindly repeats everything). The table is also called the CAM table (after the memory type). Attack: fill the table with made-up MACs (MAC flooding) → the switch is forced to flood everything → eavesdropping. The core of L2 forwarding. Related to CAM table and broadcast domain.