Quick Answer
The answer is VLAN 1. On an 802.1Q trunk, the default native VLAN is VLAN 1 on most Cisco switches, meaning traffic in this VLAN is sent untagged across the trunk link unless the native VLAN is explicitly changed. This behavior stems from the 802.1Q standard, which designates a single VLAN to carry frames without a VLAN tag for backward compatibility with devices that do not understand trunking. For the CCNA 200-301 v2 exam, this concept tests your understanding of trunking operations and the security risks of leaving the native VLAN at its default, as an attacker could potentially inject untagged frames into VLAN 1. A common trap is assuming all VLAN traffic is tagged, but the native VLAN is the exception—remember that the native VLAN is the one VLAN that remains untagged. A helpful memory tip: “Native is Naked,” meaning it travels without a tag, and by default, that naked VLAN is VLAN 1.
This 200-301 practice question tests your understanding of switching and network access. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: an 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.. 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.
On an 802.1Q trunk, which VLAN is sent untagged by default on many Cisco switches unless changed?
VLAN 10
Why wrong: VLAN 10 is not the default native VLAN.
VLAN 20
Why wrong: VLAN 20 is not the default native VLAN.
VLAN 1
Correct. VLAN 1 is the default native VLAN on many platforms.
The highest configured VLAN
Why wrong: The highest configured VLAN is unrelated to native VLAN behavior.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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.
Key principle: An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
VLAN 10
Why it's wrong here
VLAN 10 is not the default native VLAN.
When this WOULD be correct
If the exam question specified a scenario where VLAN 10 was explicitly configured as the native VLAN on a specific switch or in a particular network design, then it would be the correct answer. For example, a question could state that a network administrator has changed the default native VLAN to VLAN 10.
VLAN 20
Why it's wrong here
VLAN 20 is not the default native VLAN.
When this WOULD be correct
If the exam question specified a scenario where VLAN 20 was explicitly configured as the native VLAN on a particular Cisco switch, then VLAN 20 would be the correct answer. For example, a question could ask which VLAN is untagged on a switch where the administrator has changed the default native VLAN to 20.
VLAN 1
Why this is correct
Correct. VLAN 1 is the default native VLAN on many platforms.
Related concept
An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.
The highest configured VLAN
Why it's wrong here
The highest configured VLAN is unrelated to native VLAN behavior.
When this WOULD be correct
In a different question asking which VLAN is used as the native VLAN when a switch is configured to use the highest VLAN number as the native VLAN, option D would be correct. For instance, if a switch has VLANs 1 through 50 configured and the question specifies that the highest VLAN is set as the native VLAN, then VLAN 50 would be the answer.
Option-by-option analysis
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
Why this is correct
Correct. VLAN 1 is the default native VLAN on many platforms.
Why this is wrong here
VLAN 10 is not the default untagged VLAN on Cisco switches; instead, VLAN 1 is typically used for this purpose unless configured otherwise. Therefore, selecting VLAN 10 would be incorrect in the context of the question.
★ When this WOULD be the correct answer
If the exam question specified a scenario where VLAN 10 was explicitly configured as the native VLAN on a specific switch or in a particular network design, then it would be the correct answer. For example, a question could state that a network administrator has changed the default native VLAN to VLAN 10.
Why candidates choose this
Candidates might choose VLAN 10 due to familiarity with common VLAN configurations or because they recall that VLAN 10 is often used in various network setups, leading to confusion about default settings.
Why this is wrong here
VLAN 20 is not the default untagged VLAN on Cisco switches; instead, VLAN 1 is typically sent untagged on 802.1Q trunks unless configured otherwise. Therefore, selecting VLAN 20 does not align with the standard behavior of Cisco switch configurations.
★ When this WOULD be the correct answer
If the exam question specified a scenario where VLAN 20 was explicitly configured as the native VLAN on a particular Cisco switch, then VLAN 20 would be the correct answer. For example, a question could ask which VLAN is untagged on a switch where the administrator has changed the default native VLAN to 20.
Why candidates choose this
Candidates may choose VLAN 20 due to familiarity with VLAN configurations and assumptions that it could be a common choice for native VLANs, especially if they have encountered scenarios where VLAN 20 is used in practice.
Why this is wrong here
This option is incorrect because the default untagged VLAN on many Cisco switches is VLAN 1, not the highest configured VLAN. The highest configured VLAN can vary based on the network setup and does not have a default status in this context.
★ When this WOULD be the correct answer
In a different question asking which VLAN is used as the native VLAN when a switch is configured to use the highest VLAN number as the native VLAN, option D would be correct. For instance, if a switch has VLANs 1 through 50 configured and the question specifies that the highest VLAN is set as the native VLAN, then VLAN 50 would be the answer.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of VLAN configurations, thinking that the highest VLAN is always the default untagged VLAN, especially if they have encountered scenarios where custom configurations are used.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Be cautious not to confuse commonly used VLANs in practice with the default native VLAN set by Cisco.
Detailed technical explanation
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
Key takeaway
An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.
Real-world example
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
Review an 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Switching and Network Access — This question tests Switching and Network Access — An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default..
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.
Review an 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default., then practise related 200-301 questions on the same topic to reinforce the concept.
An 802.1Q trunk carries multiple VLANs by tagging frames with VLAN identifiers except for the native VLAN, which is sent untagged by default.
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Last reviewed: May 17, 2026
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