Port Types on a Cisco Bridge

Receiving Best BPDU: Port Type


Which type does a port become when it receives the best BPDU on a bridge?



Click on the arrows to vote for the correct answer

A. B. C. D.


In a Spanning Tree Protocol (STP) network, bridges exchange Bridge Protocol Data Units (BPDUs) to determine the root bridge and calculate the best path to reach it. BPDUs are sent out every two seconds on all ports, and the port with the lowest cost to reach the root bridge becomes the designated port.

The port on each non-root bridge with the best path to the root bridge is called the root port. The root port is responsible for forwarding frames towards the root bridge. If a bridge receives a better BPDU on a port than the current root port, that port will become the new root port.

Therefore, the correct answer to the question is D. The port becomes the root port when it receives the best BPDU on a bridge.

Option A, the designated port, is a port that has been elected to forward traffic for a particular segment. Option B, the backup port, is a port that is designated to take over forwarding duties if the designated port fails. Option C, the alternate port, is a port that is not forwarding traffic and is not a designated or root port. It is placed in a blocking state and is ready to take over forwarding duties if necessary.