How does MAC learning function?

Switches operate at Layer 2 and do not send retransmission requests; that functionality is handled by higher-layer protocols like TCP.

MAC address learning is a fundamental, default behavior on Layer 2 switches, wherein the switch automatically populates its MAC address table by examining the source MAC addresses of frames received on its active interfaces within each VLAN. This process is crucial for enabling efficient frame forwarding.

MAC learning populates the *MAC address table* with MAC addresses and their associated ingress ports, not the ARP table, which maps IP addresses to MAC addresses.

While port security (a related feature) can mitigate some attacks, MAC address learning itself is a core forwarding mechanism and is not primarily a security feature to protect against denial of service attacks.