Which option is the first criteria in MST used to choose the best path to the root bridge?
- lowest sender BID
- highest BID
- lowest root path cost
- lowest sender port ID
Explanation: In Multiple Spanning Tree (MST), once the root bridge has been identified, every non-root device must determine the most efficient path to reach it. The protocol utilizes a specific hierarchical sequence of criteria for this calculation, with the lowest root path cost being the primary and first factor considered. This cost is determined by the cumulative bandwidth of the links leading back to the root bridge, where faster links result in lower costs. If and only if multiple paths share the same minimum cost, the protocol will then proceed to evaluate subsequent tie-breakers, which include the lowest sender Bridge ID (BID) and finally the lowest sender Port ID. By prioritizing the path cost first, MST ensures that data is forwarded through the highest-capacity route available while maintaining a loop-free topology.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
