CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: a VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.. 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.
Exhibit
show interfaces status
Gi1/0/10 connected 20 a-full a-100 10/100/1000BaseTX
show vlan brief
10 Users active
30 Voice active
20 inactive
A PC connected to SW1 cannot reach the default gateway. The access port is assigned to VLAN 20, and the switch output shows that VLAN 20 is inactive. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
VLAN 20 does not exist or is not active on the switch
The port is operationally up, but VLAN 20 is listed as inactive because that VLAN does not exist in the VLAN database. An access port assigned to a missing VLAN will not carry normal user traffic for that VLAN.
Key principle: A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Port security has shut down the interface
Why it's wrong here
The interface is shown as connected, not secure-shutdown.
When this WOULD be correct
In a different scenario where a question describes a switch interface that has been configured with port security and is now in an error-disabled state due to exceeding the maximum allowed MAC addresses, this option would be correct. The question would need to focus on port security violations impacting connectivity.
✓
VLAN 20 does not exist or is not active on the switch
Why this is correct
That is exactly what the inactive VLAN status is telling you.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.
In a different scenario, if the question stated that a device needs to communicate across multiple VLANs and the access port is incorrectly configured as a trunk, then converting it to a trunk would be necessary for proper communication. This would imply that the device needs to send and receive traffic from multiple VLANs.
✗
The default gateway must be configured on the physical switch port
Why it's wrong here
Default gateways are not configured on switch access ports.
When this WOULD be correct
In a scenario where a question states that a switch port is not forwarding traffic due to a misconfigured VLAN and also mentions that the default gateway is set incorrectly on the switch, this option could be correct. For example, if the switch is expected to route traffic for multiple VLANs and the gateway is misconfigured on the switch instead of the device.
Option-by-option analysis
Why each answer is right or wrong
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.
✓VLAN 20 does not exist or is not active on the switchCorrect answer▾
Why this is correct
That is exactly what the inactive VLAN status is telling you.
✗Port security has shut down the interfaceWrong answer — click to see why▾
Why this is wrong here
This option is wrong because the question specifies that the PC cannot reach the default gateway due to VLAN issues, not because of port security settings. Port security would typically result in the interface being in an error-disabled state, which is not indicated here.
★ When this WOULD be the correct answer
In a different scenario where a question describes a switch interface that has been configured with port security and is now in an error-disabled state due to exceeding the maximum allowed MAC addresses, this option would be correct. The question would need to focus on port security violations impacting connectivity.
Why candidates choose this
Candidates may choose this option because they recognize port security as a common cause of connectivity issues on switches, leading them to associate it with the inability to reach a default gateway without fully analyzing the VLAN context provided in the question.
✗The port must be converted to a trunkWrong answer — click to see why▾
Why this is wrong here
This option is incorrect because converting the port to a trunk would not resolve the issue of the PC not reaching the default gateway if VLAN 20 is not configured or active. The problem lies in the VLAN configuration, not the port type.
★ When this WOULD be the correct answer
In a different scenario, if the question stated that a device needs to communicate across multiple VLANs and the access port is incorrectly configured as a trunk, then converting it to a trunk would be necessary for proper communication. This would imply that the device needs to send and receive traffic from multiple VLANs.
Why candidates choose this
Candidates may choose this option because they associate VLAN communication issues with trunking, believing that a trunk configuration is universally required for VLAN traffic, leading to a misunderstanding of access port functionality.
✗The default gateway must be configured on the physical switch portWrong answer — click to see why▾
Why this is wrong here
This option is incorrect because the default gateway is typically configured on the device (e.g., a router or PC) rather than on the switch port itself. The issue in the question pertains to VLAN configuration, not gateway settings.
★ When this WOULD be the correct answer
In a scenario where a question states that a switch port is not forwarding traffic due to a misconfigured VLAN and also mentions that the default gateway is set incorrectly on the switch, this option could be correct. For example, if the switch is expected to route traffic for multiple VLANs and the gateway is misconfigured on the switch instead of the device.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of where default gateway settings are applied, thinking that the switch port must have a gateway configured for VLAN traffic to flow correctly.
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
Common exam trap: answer the scenario, not the keyword
Ensure the VLAN is created and active in the VLAN database when troubleshooting connectivity issues.
Trap categories for this question
Command / output trap
The interface is shown as connected, not secure-shutdown.
Detailed technical explanation
How to think about this question
Virtual LANs (VLANs) segment a physical switch into multiple logical broadcast domains, allowing devices on the same VLAN to communicate directly. Each VLAN must be explicitly created and active in the switch's VLAN database for ports assigned to that VLAN to forward traffic correctly. When a port is configured as an access port, it tags all incoming traffic with the assigned VLAN ID internally and forwards it only to ports within the same VLAN.
If a VLAN assigned to an access port does not exist or is inactive, the switch cannot forward traffic for that VLAN. The port may show as operationally up because the physical link is active, but the VLAN inactivity prevents any Layer 2 forwarding for that VLAN. This causes devices connected to that port to lose connectivity to other VLAN members and the default gateway, which is typically configured on a Layer 3 interface or switch virtual interface (SVI) for that VLAN.
The exam trap here is assuming that a port being up means the VLAN is correctly configured and active. In reality, an access port assigned to a non-existent VLAN will not forward traffic, causing connectivity issues. Practically, network engineers must verify VLAN creation and status using commands like 'show vlan brief' to ensure the VLAN is active and properly assigned to the port, avoiding this common misconfiguration.
KKey Concepts to Remember
A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.
An access port configured with a VLAN that is inactive or missing will not carry normal user traffic, causing connectivity failures to devices like default gateways.
Switch ports assigned to access VLANs do not require trunk configuration unless they need to carry multiple VLANs simultaneously.
Default gateways are configured on Layer 3 devices or switch SVIs, not on physical Layer 2 access ports.
The operational status of a switch port being up does not guarantee that the VLAN assigned to it is active or valid.
Inactive VLANs appear in the VLAN database but are not operational, which prevents any traffic tagged or assigned to them from passing through the switch.
Switches use the VLAN database to determine which VLANs are valid and active, and ports assigned to non-existent VLANs will not forward traffic properly.
Troubleshooting VLAN connectivity issues requires verifying VLAN existence and status on the switch, especially when access ports cannot reach the default gateway.
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.
Key takeaway
A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Review a VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly., then practise related 200-301 questions on the same topic to reinforce the concept.
Switching and Network Access — This question tests Switching and Network Access — A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly..
What is the correct answer to this question?
The correct answer is: VLAN 20 does not exist or is not active on the switch — The port is operationally up, but VLAN 20 is listed as inactive because that VLAN does not exist in the VLAN database. An access port assigned to a missing VLAN will not carry normal user traffic for that VLAN.
What should I do if I get this 200-301 question wrong?
Review a VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly., then practise related 200-301 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
A VLAN must exist and be active in the VLAN database for an access port assigned to that VLAN to forward user traffic correctly.
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