- A
Cable tester
Why wrong: A standard cable tester checks continuity but does not measure voltage or PoE delivery.
- B
Tone generator
Why wrong: A tone generator traces cables but cannot measure electrical power.
- C
Multimeter
A multimeter set to DC voltage can measure the voltage on the power pairs of the Ethernet cable to verify PoE is being delivered.
- D
Wi-Fi analyzer
Why wrong: A Wi-Fi analyzer is for wireless signals, not for testing PoE on wired connections.
Question 478 of 1,020
Multimeter: Test Power over Ethernet (PoE) Voltage
This 220-1201 practice question tests your understanding of networking tools. 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 company's IT department is deploying new VoIP phones. After connecting a phone to a PoE switch, the phone does not power on. The switch port is configured for PoE and shows no errors. Which tool should be used to verify that the Ethernet cable delivers power correctly?
Quick Answer
The answer is a multimeter, because it is the correct tool to test Power over Ethernet (PoE) voltage at the endpoint. When a VoIP phone fails to power on despite a properly configured PoE switch, the issue may be a voltage drop or a break in the cable’s power pairs, and a multimeter set to DC voltage can measure the actual voltage present on pins 4-5 and 7-8 (or 1-2 and 3-6 for alternative mode) at the far end of the cable. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of hardware troubleshooting tools and PoE standards; a common trap is choosing a cable tester, which checks continuity but not voltage delivery. Remember that a cable tester tells you if the wire is connected, but only a multimeter tells you if the power is actually flowing. For a quick memory tip: “Voltage needs a voltmeter—continuity is for the cable tester.”
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
✓
Multimeter
A multimeter is the correct tool because it can measure DC voltage directly on the Ethernet cable's power-carrying pairs (typically pins 4,5 and 7,8 for Mode A or pins 1,2 and 3,6 for Mode B in 802.3af/at PoE). By probing the switch-side pins while the phone is connected, you can verify whether the switch is actually delivering the expected 48V DC, isolating a cable or power issue. This is the only tool among the options that can confirm the presence of voltage.
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.
- ✗
Cable tester
Why it's wrong here
A standard cable tester checks continuity but does not measure voltage or PoE delivery.
- ✗
Tone generator
Why it's wrong here
A tone generator traces cables but cannot measure electrical power.
- ✓
Multimeter
Why this is correct
A multimeter set to DC voltage can measure the voltage on the power pairs of the Ethernet cable to verify PoE is being delivered.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Wi-Fi analyzer
Why it's wrong here
A Wi-Fi analyzer is for wireless signals, not for testing PoE on wired connections.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose 'Cable tester' (Option A) because they assume a cable tester can verify PoE delivery, but a standard cable tester only checks continuity and pinout, not voltage or power presence.
Detailed technical explanation
How to think about this question
PoE (802.3af/at) uses a negotiation process called 'PoE classification' where the switch applies a low-voltage detection signal (2.8V to 10V) to sense a valid signature resistor (25kΩ) in the powered device before raising the voltage to 48V. If the cable has a break or high resistance on the power pairs, the switch may never complete detection, so a multimeter can reveal whether voltage is present at the phone end. In real-world troubleshooting, a faulty patch cable or a miswired keystone jack that passes a continuity test can still fail to deliver power due to excessive resistance on the power pairs, which a multimeter's voltage reading will catch.
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 practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Networking Tools — This question tests Networking Tools — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Multimeter — A multimeter is the correct tool because it can measure DC voltage directly on the Ethernet cable's power-carrying pairs (typically pins 4,5 and 7,8 for Mode A or pins 1,2 and 3,6 for Mode B in 802.3af/at PoE). By probing the switch-side pins while the phone is connected, you can verify whether the switch is actually delivering the expected 48V DC, isolating a cable or power issue. This is the only tool among the options that can confirm the presence of voltage.
What should I do if I get this 220-1201 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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Last reviewed: Jul 4, 2026
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