What action takes place when the source MAC address of a frame entering a switch appears in the MAC address table associated with a different port?

When a switch receives a frame and the source MAC address of that frame is already in the MAC address table but associated with a different port, the switch will replace the old entry and use the more current port.

In other words, the switch updates its MAC address table to reflect the new port information. This process ensures that the switch’s MAC address table remains accurate and up to date with the current network topology and device connections.

The other options provided do not accurately describe the typical behavior of a switch in this scenario:

• The switch purges the entire MAC address table: This would be an inefficient and disruptive response to a common event and is not how switches typically handle changes in the location of MAC addresses.
• The switch updates the refresh timer for the entry: The refresh timer is updated whenever a frame from the same MAC address is received on the same port, not when the MAC address is seen on a different port.
• The switch forwards the frame out of the specified port: The switch forwards frames based on the destination MAC address, not the source MAC address. The action described here does not pertain to updating the MAC address table in response to seeing a known source MAC address on a new port.