What is MAC address table aging on a Layer 2 switch, what is the typical default aging time, and what happens when an entry ages out?

• A.MAC addresses never age out; switches maintain all learned addresses permanently until the switch is rebooted. Next-hop resolution requires the next hop to be inside the destination subnet. Route poisoning advertises a failed route with metric 0 so neighbors prefer it. Policy-based routing matches only on destination address, like ordinary routing. A collapsed core design removes the access layer, cabling users into the core
• B.MAC address table aging: learned MAC-to-port mappings expire after a configurable inactivity period (default 300 seconds on most switches). When an entry ages out, the next frame destined for that MAC is treated as unknown unicast and flooded out all ports in the VLAN except the receiving port (unknown unicast flooding), until the device sends a frame and the switch re-learns its current port.
• C.