Question 150
At the Nortonwood public agency, a redundant campus ring has unexpected blocking because MST regions use different names or revision mappings. Which underlying issue most directly explains this situation?
Explanation
Correct Answer
The evidence indicates that mST region mismatches change topology interpretation and can select unexpected ports. The appropriate response is to align the intended MST region name revision and VLAN-to-instance mapping on participating switches and demonstrate that all intended switches report matching region configuration and stable root paths. This result addresses the stated challenge at the Nortonwood public agency.
Incorrect Answers
An incorrect access VLAN places untagged endpoint frames into the wrong broadcast domain. The present question instead depends on this mechanism: mST region mismatches change topology interpretation and can select unexpected ports. That difference matters for the requested root-cause explanation.
BGP neighbors require compatible AS relationships and reachable transport before exchanging routes, rather than merely a monitoring or presentation issue. The offered alternative applies that mechanism: BGP neighbors require compatible AS relationships and reachable transport before exchanging routes. The reported facts point to a different controlling condition: mST region mismatches change topology interpretation and can select unexpected ports. The alternative does not directly settle the required root-cause explanation.
A static next hop that cannot be resolved prevents the default route from forwarding traffic. In this question, the decisive issue is: mST region mismatches change topology interpretation and can select unexpected ports. That is why the offered option is not the most direct root-cause explanation.