200-301 Question 154
Single answerA network administrator is troubleshooting an issue where frames are not being forwarded correctly between two switches in a network. Upon investigation, the administrator discovers that a MAC address is missing from the MAC address table on one of the switches. How does the switch handle the frame in this scenario?
- A
The switch floods the frame out all ports except the incoming port.
- B
The switch drops the frame and sends an ICMP error message back to the sender.
- C
The switch forwards the frame to the default gateway.
- D
The switch stores the frame in a buffer and waits for the correct MAC address to be learned.
Show answer and explanation
Correct answer: A
Explanation
When a switch receives a frame with a destination MAC address that is not in its MAC address table, it uses a process called frame flooding. The switch sends the frame out to all ports except the one it was received on. This behavior ensures the frame reaches its intended recipient, assuming the recipient device is connected to one of the flooded ports. This is a fundamental operation in Layer 2 frame switching.
- A. Correct.
Correct. When a switch does not know the destination MAC address (i.e., it is not present in the MAC address table), it floods the frame out all ports except the one it was received on.
- B. Incorrect.
Incorrect. A switch does not send ICMP messages. ICMP is used in Layer 3 networking, not Layer 2 frame switching.
- C. Incorrect.
Incorrect. The switch does not forward frames to the default gateway unless specifically configured for Layer 3 routing, which is not relevant in this Layer 2 frame switching scenario.
- D. Incorrect.
Incorrect. Switches do not buffer frames indefinitely while waiting for MAC address learning. They either forward frames based on their MAC address table or flood them if the address is unknown.