200-301 Question 159
Single answerA network administrator notices high levels of traffic on a switch port. Upon investigation, it is discovered that the switch is flooding frames to all ports in the VLAN. Which situation is most likely causing this frame flooding?
- A
The destination MAC address is not in the switch's MAC address table.
- B
The switch has reached its maximum MAC address table size and cannot learn new addresses.
- C
A spanning-tree loop is causing duplicate frames in the network.
- D
The source MAC address of the frames is invalid or corrupted.
Show answer and explanation
Correct answer: A
Explanation
Frame flooding occurs when a switch receives a frame with a destination MAC address that is not in its MAC address table. Since the switch does not know which port to forward the frame to, it floods the frame to all ports in the same VLAN as a fallback mechanism. This ensures the frame reaches its intended destination, even if the MAC address is not in the table.
- A. Correct.
When the destination MAC address is not in the MAC address table, the switch floods the frame to all ports in the VLAN except the port it was received on. This is normal switch behavior.
- B. Incorrect.
If the MAC address table is full, the switch will indeed have issues learning new addresses, but this would not result in frame flooding for frames with a known destination MAC address.
- C. Incorrect.
A spanning-tree loop can cause high levels of traffic and duplicate frames, but it is not directly related to the switch's frame flooding behavior due to unknown MAC addresses.
- D. Incorrect.
Invalid or corrupted source MAC addresses can cause issues in the network, but they do not trigger frame flooding. Frame flooding occurs when the destination MAC is unknown.