The answer is VLAN tagging (802.1Q) because it allows a single switch port to carry both voice and data traffic on separate virtual LANs, ensuring that the VoIP phone and PC each receive proper network access. In this setup, the phone acts as a pass-through device, so the switch port must be configured as a trunk or access port with a voice VLAN to tag the phone’s traffic while leaving the PC’s traffic untagged. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of how to minimize cabling without sacrificing network segmentation—a common trap is confusing VLAN tagging with Power over Ethernet, which powers the phone but does not grant network access. Remember that PoE handles power, but 802.1Q handles traffic separation. A useful memory tip: “Tag the talk, leave the data plain” — voice gets a VLAN tag, data stays untagged on the same port.
220-1201 Common Networking Hardware Practice Question
This 220-1201 practice question tests your understanding of common networking hardware. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 company is deploying a new VoIP phone system. Each desk needs both a computer and a phone connected to the network. To minimize cabling, the phone will be connected to the wall jack, and the computer will connect to the phone. Which feature must the switch ports support to ensure both devices receive network access?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Why wrong: PoE provides power to the phone but does not directly ensure network access for both devices; that requires VLAN support.
B
Port mirroring
Why wrong: Port mirroring copies traffic for monitoring, not for providing network access to multiple devices.
C
VLAN tagging (802.1Q)
VLAN tagging allows the switch port to carry multiple VLANs, separating voice and data traffic so both the phone and computer can communicate on their respective networks.
D
Link aggregation
Why wrong: Link aggregation combines multiple ports for increased bandwidth, not for supporting multiple devices on a single port.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
VLAN tagging (802.1Q)
This scenario describes a typical VoIP deployment where the phone acts as a pass-through for the computer. The switch port must support VLAN tagging to separate voice and data traffic, but the key feature is Power over Ethernet (PoE) if the phone is powered by the switch. However, the question asks for both devices to receive network access, which is handled by the switch port's ability to carry multiple VLANs. The correct answer is VLAN tagging (802.1Q) to separate voice and data traffic on the same port.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
PoE (Power over Ethernet)
Why it's wrong here
PoE provides power to the phone but does not directly ensure network access for both devices; that requires VLAN support.
✗
Port mirroring
Why it's wrong here
Port mirroring copies traffic for monitoring, not for providing network access to multiple devices.
✓
VLAN tagging (802.1Q)
Why this is correct
VLAN tagging allows the switch port to carry multiple VLANs, separating voice and data traffic so both the phone and computer can communicate on their respective networks.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✗
Link aggregation
Why it's wrong here
Link aggregation combines multiple ports for increased bandwidth, not for supporting multiple devices on a single port.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
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 220-1201 question in full detail.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 220-1201 questions on switching, trunking, and access-port configuration.
Common Networking Hardware — This question tests Common Networking Hardware — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: VLAN tagging (802.1Q) — This scenario describes a typical VoIP deployment where the phone acts as a pass-through for the computer. The switch port must support VLAN tagging to separate voice and data traffic, but the key feature is Power over Ethernet (PoE) if the phone is powered by the switch. However, the question asks for both devices to receive network access, which is handled by the switch port's ability to carry multiple VLANs. The correct answer is VLAN tagging (802.1Q) to separate voice and data traffic on the same port.
What should I do if I get this 220-1201 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 220-1201 questions on switching, trunking, and access-port configuration.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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