What is the duration a switch will keep a dynamic MAC address entry if it is not seen again?

A switch maintains dynamic MAC address entries in its MAC address table for a specific duration if there is no further communication from that MAC address. The correct duration for retaining a dynamic MAC address entry is 300 seconds, or 5 minutes.

This time allows the network to accommodate nodes that may go inactive temporarily, while still cleaning up the MAC address table to remove entries that are no longer needed. After 300 seconds of inactivity, the switch will remove the MAC address from its table, which helps conserve memory and ensures that the address table remains updated with active devices. This behavior is part of the switch's functionality in managing its MAC address learning and aging process.

Understanding this timeframe is important for network design and troubleshooting, as it can affect how quickly new devices can communicate on the network and how the switch optimally manages its resources.