200-301 Question 145
Single answerA network engineer is troubleshooting an issue where two devices connected to the same VLAN on a switch cannot communicate with each other. After investigating, the engineer discovers that MAC addresses are not being learned properly and the switch's MAC address table remains empty. Which switching concept is MOST likely related to this issue?
- A
VLAN misconfiguration on the switch
- B
The switch is operating in cut-through switching mode
- C
The switch has a disabled or faulty learning process
- D
The devices are connected to different physical ports on the switch
Show answer and explanation
Correct answer: C
Explanation
The MAC address table is a core component of Layer 2 switching, as it maps MAC addresses to switch ports. If the switch's learning process is disabled or faulty, MAC addresses will not be added to the table, preventing the switch from correctly forwarding frames. This would result in devices on the same VLAN being unable to communicate.
- A. Incorrect.
VLAN misconfiguration could prevent communication between devices, but it would not result in an empty MAC address table. The MAC address table is still populated if the switch is learning MAC addresses, regardless of VLAN issues.
- B. Incorrect.
Cut-through switching mode relates to how frames are forwarded (without waiting for the entire frame to be received), but it does not affect the MAC address learning process. This is unrelated to an empty MAC address table.
- C. Correct.
If the MAC address learning process is disabled or faulty, the switch will not populate the MAC address table, resulting in communication issues between devices on the same VLAN.
- D. Incorrect.
Devices on different physical ports can communicate as long as they are configured in the same VLAN and the switch is functioning properly. This does not explain why the MAC address table is empty.