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. 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.
A phone and PC share one switchport. The phone works, but the PC cannot reach its normal data resources. The switchport voice VLAN is configured, and the access VLAN is incorrect. Which explanation is strongest?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The PC is likely in the wrong data VLAN even though the phone still uses the correct voice VLAN.
Option A is correct because the switchport is configured with a voice VLAN for the phone and an access VLAN for the PC. If the access VLAN is incorrect, the PC will be placed in the wrong data VLAN, preventing it from reaching its normal data resources, while the phone continues to operate correctly on its designated voice VLAN. This is a common misconfiguration where the data VLAN ID does not match the network segment the PC expects.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The PC is likely in the wrong data VLAN even though the phone still uses the correct voice VLAN.
Why this is correct
This is correct because voice and data use different VLAN roles on the same physical port.
Related concept
Read the scenario before looking for a memorised answer.
✗
If the phone works, the PC must also work because both use the same VLAN always.
Why it's wrong here
This is wrong because the phone and PC can use different VLANs on that port.
When this WOULD be correct
In a different scenario where both devices are explicitly stated to be on the same VLAN and the question focuses on a situation where a misconfiguration affects both devices equally, this option could be correct. For example, if the question specified that both the phone and PC are configured on the same VLAN and the VLAN is down, then this option would apply.
✗
The issue must be BGP because phones cannot use VLANs.
Why it's wrong here
This is wrong because the scenario is clearly about voice/data VLAN separation.
When this WOULD be correct
In a different question setup where the context involves a network configuration issue specifically related to BGP routing and VLANs, this option could be correct if the question states that BGP is misconfigured, causing devices on the same VLAN to fail to communicate. For example, if the question describes a scenario where both devices are on the same VLAN but cannot reach external resources due to BGP issues.
✗
The access VLAN becomes irrelevant whenever a voice VLAN is configured.
Why it's wrong here
This is wrong because the access VLAN still matters for the PC's data traffic.
When this WOULD be correct
In a scenario where a switchport is configured to only support voice traffic and is set to trunk mode without any access VLAN specified, this option could be correct. For example, if the question states that the switchport is exclusively for voice traffic and does not allow data traffic, then the access VLAN would indeed be irrelevant.
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.
✓The PC is likely in the wrong data VLAN even though the phone still uses the correct voice VLAN.Correct answer▾
Why this is correct
This is correct because voice and data use different VLAN roles on the same physical port.
✗If the phone works, the PC must also work because both use the same VLAN always.Wrong answer — click to see why▾
Why this is wrong here
This statement is incorrect because the phone and PC can operate on different VLANs on the same port. The phone uses the voice VLAN, while the PC uses the access (data) VLAN. They are not required to use the same VLAN, and misconfiguration of the access VLAN can cause the PC to fail while the phone works.
★ When this WOULD be the correct answer
In a different scenario where both devices are explicitly stated to be on the same VLAN and the question focuses on a situation where a misconfiguration affects both devices equally, this option could be correct. For example, if the question specified that both the phone and PC are configured on the same VLAN and the VLAN is down, then this option would apply.
Why candidates choose this
Students might assume that since both devices share the same physical port, they must be on the same VLAN. This confusion arises from a lack of understanding of how voice VLANs work, where the switchport is configured to carry multiple VLANs and the phone is placed on a separate VLAN from the PC.
✗The issue must be BGP because phones cannot use VLANs.Wrong answer — click to see why▾
Why this is wrong here
BGP (Border Gateway Protocol) is a routing protocol used between autonomous systems, not related to VLAN configuration on a switchport. The issue described is about Layer 2 VLAN assignment, not Layer 3 routing. BGP has no role in this scenario.
★ When this WOULD be the correct answer
In a different question setup where the context involves a network configuration issue specifically related to BGP routing and VLANs, this option could be correct if the question states that BGP is misconfigured, causing devices on the same VLAN to fail to communicate. For example, if the question describes a scenario where both devices are on the same VLAN but cannot reach external resources due to BGP issues.
Why candidates choose this
Students might confuse BGP with other protocols or think that any network issue involving phones must involve a routing protocol. The mention of 'phones' might trigger an association with VoIP and routing, but the problem is clearly about VLANs, not BGP.
✗The access VLAN becomes irrelevant whenever a voice VLAN is configured.Wrong answer — click to see why▾
Why this is wrong here
The access VLAN remains relevant even when a voice VLAN is configured. The access VLAN is used for the PC's data traffic, while the voice VLAN is used for the phone's traffic. If the access VLAN is incorrect, the PC will not be able to communicate on the correct data network.
★ When this WOULD be the correct answer
In a scenario where a switchport is configured to only support voice traffic and is set to trunk mode without any access VLAN specified, this option could be correct. For example, if the question states that the switchport is exclusively for voice traffic and does not allow data traffic, then the access VLAN would indeed be irrelevant.
Why candidates choose this
Students might think that configuring a voice VLAN overrides or makes the access VLAN unnecessary. However, both VLANs are active on the port, and the access VLAN still determines the VLAN for untagged data traffic from the PC.
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
Cisco often tests the misconception that a working phone implies the PC is also correctly configured, but the trap here is that voice and data VLANs are independent, so a misconfigured access VLAN only affects the PC.
Trap categories for this question
Scenario analysis trap
This is wrong because the scenario is clearly about voice/data VLAN separation.
Detailed technical explanation
How to think about this question
When a Cisco IP phone is connected to a switchport configured with a voice VLAN, the phone uses CDP or LLDP to negotiate the voice VLAN ID and tags its traffic with an 802.1Q header, while the PC remains untagged in the access VLAN. The switchport command 'switchport voice vlan <vlan-id>' separates the traffic, and if the access VLAN is misconfigured (e.g., VLAN 10 instead of VLAN 20), the PC will be isolated from its intended subnet. In real-world scenarios, this often occurs after a VLAN renumbering where the access VLAN is not updated on the interface.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Switching and Network Access — This question tests Switching and Network Access — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The PC is likely in the wrong data VLAN even though the phone still uses the correct voice VLAN. — Option A is correct because the switchport is configured with a voice VLAN for the phone and an access VLAN for the PC. If the access VLAN is incorrect, the PC will be placed in the wrong data VLAN, preventing it from reaching its normal data resources, while the phone continues to operate correctly on its designated voice VLAN. This is a common misconfiguration where the data VLAN ID does not match the network segment the PC expects.
What should I do if I get this 200-301 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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