easyMultiple ChoiceObjective-mapped
200-901 Practice Question: An engineer notices that a switch port configured…
An engineer notices that a switch port configured as an access port in VLAN 10 is not forwarding traffic. The switch shows the port is up/up. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that an access port can handle tagged frames, leading candidates to overlook the strict untagged-only behavior of access ports.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The connected device is sending 802.1Q tagged frames
An access port expects to receive and send only untagged frames, as it belongs to a single VLAN (VLAN 10). If the connected device sends 802.1Q tagged frames, the switch will drop them because the access port does not process VLAN tags. This explains why the port is up/up but not forwarding traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Spanning Tree Protocol blocking the port
Why it's wrong here
STP blocking would show in show spanning-tree.
- ✓
The connected device is sending 802.1Q tagged frames
Why this is correct
Access ports drop tagged frames.
- ✗
Speed/duplex mismatch
Why it's wrong here
Would cause errors or down state.
- ✗
VLAN 10 does not exist in the VLAN database
Why it's wrong here
VLAN 10 would be created automatically if not present.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-901 exam.