Which of these is the calculation used to determine the root port in the spanning-tree calculation?
- the first port that becomes active
- the port with the fastest speed
- the port with the lowest cost to the root
- the port that the neighbor switch will forward traffic to
Explanation: In the Spanning Tree Protocol (STP) operation, after the root bridge has been elected, every non-root bridge must determine its best path back to that root bridge. The switch achieves this by evaluating the cumulative path cost, which represents the sum of the costs of all links leading to the root. The specific interface that offers the lowest cost to the root is designated as the root port. While these path costs are calculated based on the bandwidth of the links by default, the final decision in the spanning-tree calculation specifically relies on identifying the port with the minimum cumulative cost value to ensure the most efficient, loop-free path is selected for traffic forwarding.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
