Which statement about CAM table aging is true?

Which statement about CAM table aging is true?

• A. Entries never age.
• B. Entries age out after a period of inactivity.
• C. Aging increases CAM size automatically.
• D. Aging causes frames to be dropped.

Answer: (B)

CAM table aging keeps the MAC address table lively by removing entries that aren’t used for a while. A switch learns where devices are by inspecting source MAC addresses on frames and storing the MAC with the port it was seen on. To avoid wasting memory on devices that are gone or have moved, each learned entry has an aging timer. If that device stops sending frames and the timer runs out, the entry is deleted. When the device next transmits, the switch learns its MAC again—potentially on a different port if the device moved—so the table stays accurate and memory isn’t tied up by stale entries. That’s why the statement that entries age out after inactivity is the correct one. CAM size doesn’t automatically increase due to aging, and aging itself doesn’t drop frames; it only removes old entries so the switch can relearn as needed. Aging timers are typically a matter of minutes and are reset by activity from the associated MAC.

CAM table aging keeps the MAC address table lively by removing entries that aren’t used for a while. A switch learns where devices are by inspecting source MAC addresses on frames and storing the MAC with the port it was seen on. To avoid wasting memory on devices that are gone or have moved, each learned entry has an aging timer. If that device stops sending frames and the timer runs out, the entry is deleted. When the device next transmits, the switch learns its MAC again—potentially on a different port if the device moved—so the table stays accurate and memory isn’t tied up by stale entries. That’s why the statement that entries age out after inactivity is the correct one. CAM size doesn’t automatically increase due to aging, and aging itself doesn’t drop frames; it only removes old entries so the switch can relearn as needed. Aging timers are typically a matter of minutes and are reset by activity from the associated MAC.