Question 53 of 2,015
VLANs and TrunkingmediumDrag & DropObjective-mapped

Quick Answer

The correct order for Q-in-Q configuration steps is: enable the feature globally, configure the trunk port as a dot1q tunnel port, set the native VLAN, apply the service instance to encapsulate traffic, and finally verify with show interfaces dot1q-tunnel. This sequence is technically required because 802.1ad double-tagging must first be activated at the global level before any port can operate as a tunnel endpoint; the trunk port must then be set to dot1q-tunnel mode to accept outer tags, followed by defining the native VLAN to prevent misconfiguration of untagged frames, and the service instance binds the inner tag encapsulation. On the ENCOR 350-401 exam, this drag-and-drop task tests your understanding of service provider bridging and the logical dependency of each step—a common trap is placing verification before the service instance or forgetting that global enablement comes first. Remember the mnemonic “Global, Tunnel, Native, Service, Show” to lock in the order.

350-401 VLANs and Trunking Practice Question

This 350-401 practice question tests your understanding of vlans and trunking. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Drag and drop the steps of Q-in-Q (802.1ad) double-tagging configuration into the correct order, from first to last.

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "first"

    Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

Question 1mediumdrag order
Full question →

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

Enable Q-in-Q globally with vlan dot1q tag native

Q-in-Q configuration requires first enabling the feature globally, then configuring the trunk port as a dot1q tunnel port, setting the native VLAN, and finally applying the service instance to encapsulate traffic. Verification ensures proper double-tagging.

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Common exam traps

Common exam trap: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

  • Access ports place end devices into a single VLAN.
  • Trunk ports carry multiple VLANs between switches.
  • Allowed VLAN lists decide which VLANs can cross a trunk.
  • Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

  • Use show vlan brief to verify access VLANs.
  • Use show interfaces trunk to verify trunk state and allowed VLANs.
  • Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Real-world example

How this comes up in practice

A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.

Related practice questions

Related 350-401 practice-question pages

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FAQ

Questions learners often ask

What does this 350-401 question test?

VLANs and Trunking — This question tests VLANs and Trunking — Access ports place end devices into a single VLAN..

What is the correct answer to this question?

The correct answer is: Enable Q-in-Q globally with vlan dot1q tag native — Q-in-Q configuration requires first enabling the feature globally, then configuring the trunk port as a dot1q tunnel port, setting the native VLAN, and finally applying the service instance to encapsulate traffic. Verification ensures proper double-tagging.

What should I do if I get this 350-401 question wrong?

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.

Are there clue words in this question I should notice?

Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

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Same concept, more angles

1 more ways this is tested on 350-401

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. Drag and drop the steps of Q-in-Q (802.1ad) double-tagging configuration into the correct order, from first to last.

medium
  • A.Enable dot1q tunneling globally
  • B.Configure access VLAN on interface
  • C.Set interface mode to dot1q-tunnel
  • D.Configure native VLAN for untagged traffic
  • E.Verify with show dot1q-tunnel

Why A: First enable the dot1q tunnel globally, then configure the access VLAN on the interface, enable the tunnel mode, and set the native VLAN to avoid conflicts.

Last reviewed: Jun 18, 2026

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This 350-401 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 350-401 exam.