Question 210
At a design studio in Berlin, engineers report that a downstream switch places untagged frames into a different native VLAN than the aggregation switch. The work affects wireless workstations and video conferences. What evidence should the engineer request after the repair?
Explanation
Correct Answer
This observation tests the VLAN trunk and native VLAN consistency requirement at a design studio in Berlin. The expected result is that tagged and untagged test frames enter their intended VLANs on both ends and unauthorized VLANs are not carried. The necessary correction is to match the switchport tagging, native VLAN and allowed VLAN list on each end of the campus trunk; a saved configuration alone would not prove it is working. In this case, the observed fault is that a downstream switch places untagged frames into a different native VLAN than the aggregation switch.
Incorrect Answers
At a design studio in Berlin, the observation may be useful for a separate Ingress ACL enforcement and least privilege test, but it does not establish that a downstream switch places untagged frames into a different native VLAN than the aggregation switch has been resolved. The relevant check is the VLAN trunk and native VLAN consistency outcome.
At a design studio in Berlin, this measures a different network requirement, LACP aggregation and member consistency. The case describes that a downstream switch places untagged frames into a different native VLAN than the aggregation switch, so accepting this result would leave the primary fault without direct verification.
At a design studio in Berlin, this would verify RSTP root election and loop prevention, not the failure reported in this scenario. The requested closure criterion instead concerns VLAN trunk and native VLAN consistency: tagged and untagged test frames enter their intended VLANs on both ends and unauthorized VLANs are not carried.