What addressing information is recorded by a switch to build its MAC address table?

A switch builds its MAC address table, also known as a forwarding table, by recording the following addressing information:

1. MAC Address: This is the unique identifier assigned to a network interface controller (NIC) for communications at the data link layer of a network segment. The switch records the MAC address of each device connected to each of its ports.

2. Switch Port: The switch records the port number that each connected device is attached to. This allows the switch to direct traffic appropriately.

3. VLAN Information: If VLANs are being used, the switch also records the VLAN ID associated with each MAC address. This allows the switch to keep traffic from different VLANs separate.

4. Timestamp: The switch records the time when the MAC address was learned. This is used to age out old entries in the table.

The switch learns this information dynamically as it receives frames. When a frame comes in, the switch looks at the source MAC address and adds it to the MAC address table, along with the port number that the frame was received on and the current time. If the MAC address is already in the table, the switch updates the timestamp.