- A
Configure the port as a trunk and allow both VLANs.
Why wrong: This is incorrect because the port should remain an access port, not a trunk. Trunk ports are used for switch-to-switch or switch-to-router links, not for end devices like phones and PCs.
- B
Use the 'switchport voice vlan' command to assign a dedicated voice VLAN.
This command separates voice traffic from data traffic by placing the phone in a specific VLAN, typically VLAN 10 or similar, while the PC remains in the native access VLAN.
- C
Disable spanning tree on the port to prevent voice delays.
Why wrong: Disabling spanning tree is dangerous and unnecessary; STP prevents loops and should remain enabled. Voice delays are better managed by QoS and proper VLAN configuration.
- D
Apply 'mls qos trust cos' on the interface to preserve voice packet markings.
Cisco IP phones mark voice packets with CoS value 5. Trusting these markings on the access port ensures that the QoS policy in the network treats voice traffic with priority.
- E
Configure the port as a routed port with an IP address for management.
Why wrong: Routed ports are used for Layer 3 connectivity between routers or switches, not for connecting end devices like phones and PCs. This would break VLAN segmentation.
Quick Answer
The correct answer is to apply both the `switchport voice vlan` command and `mls qos trust cos` on the interface. The `switchport voice vlan` command assigns a dedicated VLAN for voice traffic, allowing the Cisco IP phone to tag its packets with the voice VLAN ID while the desktop PC remains in the native data VLAN, effectively separating traffic on a single access port. The `mls qos trust cos` command preserves the Layer 2 Class of Service markings from the IP phone, ensuring voice packets receive appropriate QoS treatment across the network—critical for preventing jitter and delay. On the CCNA 200-301 v2 exam, this scenario tests your understanding of how a single switch port can carry both data and voice VLANs without needing a trunk, a common trap where candidates mistakenly enable trunking or disable Spanning Tree Protocol. Remember the memory tip: “Voice tags, data stays; trust CoS for voice delays.”
CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. 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.
Which TWO switch port configurations are required when connecting a Cisco IP phone and a desktop PC to a single access port?
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
Use the 'switchport voice vlan' command to assign a dedicated voice VLAN.
Option B is correct because the 'switchport voice vlan' command assigns a dedicated VLAN for voice traffic, allowing the IP phone to tag its packets with the voice VLAN ID while the PC remains in the native (data) VLAN. Option D is correct because 'mls qos trust cos' preserves the Layer 2 Class of Service (CoS) markings from the IP phone, ensuring voice packets receive appropriate QoS treatment across the network. Option A is incorrect because a trunk port is not required—the access port with the voice VLAN command handles both VLANs without trunking. Option C is incorrect because disabling Spanning Tree Protocol (STP) is not a recommended practice and does not prevent voice delays; STP is essential for loop prevention and can be tuned with PortFast instead. Option E is incorrect because the port must remain a Layer 2 access port, not a routed port, to support both the PC and IP phone.
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.
- ✗
Configure the port as a trunk and allow both VLANs.
Why it's wrong here
This is incorrect because the port should remain an access port, not a trunk. Trunk ports are used for switch-to-switch or switch-to-router links, not for end devices like phones and PCs.
- ✓
Use the 'switchport voice vlan' command to assign a dedicated voice VLAN.
Why this is correct
This command separates voice traffic from data traffic by placing the phone in a specific VLAN, typically VLAN 10 or similar, while the PC remains in the native access VLAN.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Disable spanning tree on the port to prevent voice delays.
- ✓
Apply 'mls qos trust cos' on the interface to preserve voice packet markings.
Why this is correct
Cisco IP phones mark voice packets with CoS value 5. Trusting these markings on the access port ensures that the QoS policy in the network treats voice traffic with priority.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure the port as a routed port with an IP address for management.
Why it's wrong here
Routed ports are used for Layer 3 connectivity between routers or switches, not for connecting end devices like phones and PCs. This would break VLAN segmentation.
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.
✓Use the 'switchport voice vlan' command to assign a dedicated voice VLAN.Correct answer▾
Why this is correct
This command separates voice traffic from data traffic by placing the phone in a specific VLAN, typically VLAN 10 or similar, while the PC remains in the native access VLAN.
✗Configure the port as a trunk and allow both VLANs.Wrong answer — click to see why▾
Why this is wrong here
Using a trunk port for a single device connection is unnecessary and violates standard access port design; it would also require the phone to support trunking, which is not the typical Cisco IP phone configuration.
✗Disable spanning tree on the port to prevent voice delays.Wrong answer — click to see why▾
Why this is wrong here
STP does not introduce significant delays in normal operation, and disabling it risks broadcast storms and network loops.
✗Configure the port as a routed port with an IP address for management.Wrong answer — click to see why▾
Why this is wrong here
Access ports operate at Layer 2; converting to a routed port would prevent the phone and PC from communicating within their respective VLANs.
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 trunk port is needed to carry both voice and data VLANs, but the correct approach uses a single access port with the 'switchport voice vlan' command to handle both VLANs without trunking.
Detailed technical explanation
How to think about this question
When a Cisco IP phone is connected to a switch port configured with 'switchport voice vlan', the phone uses Cisco Discovery Protocol (CDP) to learn the voice VLAN ID and then tags its frames with that VLAN. The PC connected to the phone's pass-through port remains untagged in the native (data) VLAN. The 'mls qos trust cos' command (Option D) is also correct because it preserves the CoS markings from the phone, ensuring that voice packets receive appropriate priority across the network; without this, the switch would re-mark or ignore the CoS values, potentially degrading voice quality.
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.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 200-301 question test?
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: Use the 'switchport voice vlan' command to assign a dedicated voice VLAN. — Option B is correct because the 'switchport voice vlan' command assigns a dedicated VLAN for voice traffic, allowing the IP phone to tag its packets with the voice VLAN ID while the PC remains in the native (data) VLAN. Option D is correct because 'mls qos trust cos' preserves the Layer 2 Class of Service (CoS) markings from the IP phone, ensuring voice packets receive appropriate QoS treatment across the network. Option A is incorrect because a trunk port is not required—the access port with the voice VLAN command handles both VLANs without trunking. Option C is incorrect because disabling Spanning Tree Protocol (STP) is not a recommended practice and does not prevent voice delays; STP is essential for loop prevention and can be tuned with PortFast instead. Option E is incorrect because the port must remain a Layer 2 access port, not a routed port, to support both the PC and IP phone.
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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Same concept, more angles
1 more ways this is tested on 200-301
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. Which TWO statements correctly describe the configuration and use of a voice VLAN on a Cisco switch port?
medium- A.The voice VLAN is configured using the 'switchport mode trunk' command.
- ✓ B.When a voice VLAN is configured, the switch port operates in two VLANs: one for data and one for voice traffic.
- C.The voice VLAN must be the same as the native VLAN on the trunk link.
- ✓ D.The IP phone uses CDP or LLDP to learn the voice VLAN ID from the switch.
- E.The data VLAN and voice VLAN must be in the same IP subnet.
Why B: Option B is correct because when a voice VLAN is configured on a Cisco switch port, the port operates in two separate VLANs simultaneously: one for data traffic (the access VLAN) and one for voice traffic (the voice VLAN). This is achieved using the 'switchport voice vlan' command, which allows the switch to tag voice frames with the voice VLAN ID while leaving data frames untagged (or tagged with the access VLAN). This separation ensures that voice traffic receives appropriate QoS treatment and is isolated from data traffic.
Last reviewed: Jun 11, 2026
This 200-301 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 200-301 exam.
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