CCNA: Cisco Certified Network Associate — Question 471

What happens when a switch receives a frame with a destination MAC address that recently aged out?

Answer options

• A. The switch floods the frame to all ports in all VLANs except the port that received the frame.
• B. The switch floods the frame to all ports in the VLAN except the port that received the frame.
• C. The switch references the MAC address aging table for historical addresses on the port that received the frame.
• D. The switch drops the frame and learns the destination MAC address again from the port that received the frame.

Correct answer: B

Explanation

The correct answer is B because when a frame's destination MAC address is not found in the switch's MAC address table, the switch will flood the frame within the same VLAN to all ports except the one it was received on. Option A is incorrect as it mentions all VLANs instead of just the relevant VLAN. Option C is wrong because the switch does not reference the aging table for a recently timed out address. Option D is also incorrect as the switch does not drop the frame but floods it instead.