The answer is an 802.3af and 802.3bt standard mismatch, where the camera requires PoE++ but the switch only supports PoE. This is the most likely cause because 802.3af (PoE) delivers a maximum of 15.4W per port, while 802.3bt (PoE++) can supply up to 60W or 90W; if the camera’s power demand exceeds the switch’s capability, the device will not power on even with PoE enabled and a functional cable. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding of PoE standards and power budgets, often appearing as a troubleshooting question where the trap is assuming any PoE port will work for any PoE device. A common memory tip is to remember the wattage progression: 802.3af (15.4W) is “af-fordable” for basic devices, 802.3at (30W) is “at-let” for mid-range gear, and 802.3bt (60-90W) is “big-ticket” for high-power equipment like pan-tilt-zoom cameras.
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. 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 network administrator is deploying a new PoE security camera. The camera is connected to a PoE-enabled switch port, but the camera does not power on. The administrator confirms the switch port has PoE enabled and the cable is tested and functional. 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
✓
The camera requires 802.3bt (PoE++), but the switch only supports 802.3af (PoE).
The camera requires 802.3bt (PoE++) which can deliver up to 60W or 90W, but the switch only supports 802.3af (PoE) which provides a maximum of 15.4W per port. Since the camera's power demand exceeds the switch's capability, the camera will not power on even though PoE is enabled and the cable is functional.
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 cable is a crossover cable.
Why it's wrong here
Modern switches and cameras support Auto-MDIX, so a crossover cable should work fine.
✓
The camera requires 802.3bt (PoE++), but the switch only supports 802.3af (PoE).
Why this is correct
The power output of 802.3af may be insufficient for a camera that needs the higher power of 802.3bt.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The port is configured as an access port.
Why it's wrong here
VLAN mode (access/trunk) does not affect PoE power delivery.
✗
The camera is using a passive PoE injector.
Why it's wrong here
Passive injectors may cause issues if not matched, but the most common cause is a power standard mismatch.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume any PoE switch will power any PoE device, overlooking the critical power budget differences between 802.3af, 802.3at, and 802.3bt standards.
Detailed technical explanation
How to think about this question
802.3af (PoE) uses two wire pairs to deliver up to 15.4W, while 802.3bt (PoE++) uses all four pairs to deliver up to 90W. The switch and camera perform a physical-layer classification handshake during power-up; if the camera requests a power class that the switch cannot supply, the switch will not apply power, resulting in the camera remaining off. In real-world deployments, high-power devices like pan-tilt-zoom cameras or LED lighting often require 802.3bt, and using an 802.3af switch will cause a no-power condition.
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 N10-009 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
Network Troubleshooting — This question tests Network Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The camera requires 802.3bt (PoE++), but the switch only supports 802.3af (PoE). — The camera requires 802.3bt (PoE++) which can deliver up to 60W or 90W, but the switch only supports 802.3af (PoE) which provides a maximum of 15.4W per port. Since the camera's power demand exceeds the switch's capability, the camera will not power on even though PoE is enabled and the cable is functional.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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