Ethernet switches add entries to their MAC address table based on what field of the Ethernet frame?

Ethernet switches add entries to their MAC address table based on the Source Address field of the Ethernet frame. Here's the step-by-step process:

1. When a frame arrives at an Ethernet switch, the switch examines the frame's source MAC address.
2. The switch then checks its MAC address table to see if it already has an entry for that source MAC address.
3. If the switch does not have an entry for the source MAC address, it adds an entry to its MAC address table. The entry includes the source MAC address and the port number where the frame arrived.
4. If the switch already has an entry for the source MAC address, it updates the entry with the new port number.
5. The switch then uses the destination MAC address to forward the frame to the appropriate port. If the destination MAC address is not in the MAC address table, the switch forwards the frame to all ports except the one where the frame arrived.