What is a MAC address learned by a switch without manual configuration called?

A MAC address learned by a switch without manual configuration is referred to as a dynamic MAC address. When a switch receives frames on its ports, it examines the source MAC address of the incoming frame and adds this address to its MAC address table along with the corresponding port number. This learning process occurs automatically and continuously based on traffic flow.

Dynamic MAC addresses play a critical role in building a switch’s MAC address table, allowing it to forward frames efficiently only to the necessary ports where the destination devices are connected. They are temporary, as they can be aged out after a period of inactivity, allowing the switch to make room for new dynamic entries as needed. This automatic learning and management help maintain a flexible and efficient network without requiring manual entry for each MAC address.

In contrast, static MAC addresses are manually configured and do not change or age out, while default or virtual MAC addresses do not pertain to the automatic learning mechanism of standard Ethernet network operations.