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On an 802.1Q trunk, which VLAN is sent untagged by default on many Cisco switches unless changed?

Question 1mediummultiple choice
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On an 802.1Q trunk, which VLAN is sent untagged by default on many Cisco switches unless changed?

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Answer choices

Why each option matters

Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.

A

Distractor review

VLAN 10

VLAN 10 is not the default native VLAN.

B

Distractor review

VLAN 20

VLAN 20 is not the default native VLAN.

C

Best answer

VLAN 1

Correct. VLAN 1 is the default native VLAN on many platforms.

D

Distractor review

The highest configured VLAN

The highest configured VLAN is unrelated to native VLAN behavior.

Common exam trap

Common exam trap: answer the scenario, not the keyword

{"title":"Native VLAN Mismatch","description":"If the Native VLAN doesn't match on both ends of a trunk, traffic will leak between different VLANs, creating a major security risk."}

Technical deep dive

How to think about this question

Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.

KKey Concepts to Remember

  • An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.
  • Cisco switches assign VLAN 1 as the default native VLAN, meaning VLAN 1 traffic is transmitted untagged on 802.1Q trunk links unless changed.
  • The native VLAN allows compatibility with devices or protocols that do not support VLAN tagging by sending its traffic untagged.
  • Changing the native VLAN from VLAN 1 is a common security best practice to prevent VLAN hopping attacks in Cisco networks.
  • Frames belonging to VLANs other than the native VLAN are always tagged on an 802.1Q trunk to maintain VLAN separation.
  • The native VLAN setting affects how switches handle untagged frames received on trunk ports, associating them with the native VLAN.
  • Misunderstanding the native VLAN default can lead to configuration errors and security vulnerabilities in Cisco network designs.
  • The exam tests knowledge of default Cisco behaviors, so knowing VLAN 1 is the default native VLAN is essential for the CCNA 200-301 exam.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

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More questions from this exam

Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.

Question 1

A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?

Question 2

A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?

Question 3

What is the OSPF metric called?

Question 4

A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?

Question 5

A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?

Question 6

A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?

FAQ

Questions learners often ask

What does this 200-301 question test?

An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.

What is the correct answer to this question?

The correct answer is: VLAN 1 — On many Cisco platforms, VLAN 1 is the default native VLAN. Native VLAN traffic is sent untagged unless the native VLAN is changed.

What should I do if I get this 200-301 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.

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