Which field of an Ethernet frame is utilized by a switch to learn and update its MAC address table?

The Source MAC Address field of an Ethernet frame is crucial for a switch to learn and update its MAC address table. When a switch receives a frame, it examines the source MAC address contained in that frame. This information is vital because it allows the switch to map the MAC address to the port on which the frame was received. By doing so, the switch can build its MAC address table, which is essential for efficient packet forwarding.

As the switch processes subsequent frames, it can refer back to this table to determine which port to send a particular frame out of, based on its destination MAC address. This learning process enables switches to operate more effectively, reducing network traffic and collisions by ensuring that frames are only sent to the specific port associated with the destination MAC address.

In context, while the other fields of the Ethernet frame, such as the Destination MAC Address, EtherType Field, and Checksum Field, serve differing roles—such as identifying where to send the frame, indicating the protocol type, or ensuring data integrity—they do not contribute to the learning process of the MAC address table in the same direct manner as the Source MAC Address does.