The answer is a power budget mismatch, specifically that the AP is not receiving enough power from the switch. An 802.3at (PoE+) access point requires up to 25.5 watts, but an 802.3af (PoE) switch caps at 15.4 watts per port; the AP powers on at the lower tier but under load—such as transmitting with multiple radios—it draws more current than the switch can supply, causing voltage droop and intermittent resets or link drops. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding of PoE standards and power negotiation, often appearing as a trap where a device “boots” but fails under load, misleading candidates into blaming cable length or interference. Remember the mnemonic: “AF is half, AT is full—if it boots but drops, the watts aren’t enough.”
N10-009 Network Implementation Practice Question
This N10-009 practice question tests your understanding of network implementation. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 technician installs a new 802.3at (PoE+) access point in a warehouse. The AP is connected via a 200-foot Cat5e cable to a switch that only supports 802.3af (PoE). The AP powers on but experiences intermittent connectivity drops. 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 AP is not receiving enough power from the switch
The switch only supports 802.3af (PoE), which provides a maximum of 15.4 watts per port, while the 802.3at (PoE+) access point requires up to 25.5 watts to operate reliably. The AP powers on because it can negotiate 802.3af power, but under load (e.g., transmitting at higher power or using multiple radios), it draws more current than the switch can supply, causing voltage droop and intermittent resets or link drops. This is a classic power budget mismatch scenario.
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 length exceeds the maximum allowed for PoE
Why it's wrong here
Cat5e supports PoE up to 100 meters (328 feet). 200 feet is well within that limit.
✓
The AP is not receiving enough power from the switch
Why this is correct
The AP requires PoE+ (802.3at), but the switch only provides PoE (802.3af). The insufficient power can cause the AP to function erratically.
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.
✗
Duplex mismatch between the AP and the switch
Why it's wrong here
Duplex mismatch would cause errors but is less likely than power inadequacy given the known PoE standard difference.
✗
Radio frequency interference from warehouse equipment
Why it's wrong here
RF interference could affect wireless performance but would not cause power-related intermittent connectivity on the wired PoE connection.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see the AP powers on and assume power is sufficient, overlooking that 802.3at devices can operate at reduced functionality on 802.3af but will fail under higher load, leading them to incorrectly blame cable length or RF interference instead of the power budget mismatch.
Detailed technical explanation
How to think about this question
802.3af (PoE) delivers 15.4W at the PSE (Power Sourcing Equipment) with a minimum of 12.95W at the PD (Powered Device) after cable losses, while 802.3at (PoE+) delivers 25.5W at the PSE with a minimum of 25.0W at the PD. When a PoE+ AP is connected to an 802.3af switch, the AP may initially power on using the lower power class (Class 0-3), but if it attempts to draw more than 15.4W (e.g., during high-throughput operation), the switch's PSE will either current-limit or shut down the port, causing the AP to reboot. This is often misdiagnosed as a cable or interference issue because the failure is intermittent and load-dependent.
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 Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The AP is not receiving enough power from the switch — The switch only supports 802.3af (PoE), which provides a maximum of 15.4 watts per port, while the 802.3at (PoE+) access point requires up to 25.5 watts to operate reliably. The AP powers on because it can negotiate 802.3af power, but under load (e.g., transmitting at higher power or using multiple radios), it draws more current than the switch can supply, causing voltage droop and intermittent resets or link drops. This is a classic power budget mismatch scenario.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. A network engineer needs to install 15 wireless access points that each require 25W of power. The available switch provides PoE+ (802.3at) with a total power budget of 740W. The engineer also needs to connect 10 IP cameras that each require 12W. Which of the following should the engineer verify before proceeding with the installation?
easy
✓ A.The total power consumption of all devices does not exceed the switch's power budget.
B.The switch supports LLDP-MED for power negotiation.
C.All PoE devices are from the same manufacturer.
D.The cable length does not exceed 150 meters.
Why A: The total power required is 15 APs × 25W + 10 cameras × 12W = 375W + 120W = 495W, which is well below the switch's 740W PoE+ budget. However, the engineer must verify that the cumulative power draw does not exceed the budget, as exceeding it would cause some ports to be denied power or shut down. This is the fundamental prerequisite for any PoE deployment.
Variation 2. A network technician is installing a new wireless access point in a warehouse. The AP requires PoE+ (802.3at) for full operation. The technician connects the AP using a Cat5e cable run of 200 feet to a switch that only supports 802.3af (PoE). The AP powers on but has intermittent connectivity issues. What is the most likely cause?
medium
A.The cable length exceeds the maximum for PoE
✓ B.The switch does not support the required PoE standard
C.The AP is experiencing interference from metal racks
D.The AP is configured with the wrong SSID
Why B: The switch only supports 802.3af (PoE), which provides up to 15.4W per port, while the AP requires 802.3at (PoE+) for full operation, which supplies up to 30W. Although the AP powers on, it may not receive sufficient power to operate all radios or features, leading to intermittent connectivity issues. The cable length of 200 feet is within the 100-meter (328-foot) limit for Cat5e, so length is not the problem.
Variation 3. A technician installs a new wireless access point that requires 25 watts of power using Power over Ethernet (PoE). The existing switch only supports 802.3af (15.4W per port). What is the most likely result?
medium
A.The access point will power on but may not transmit at full power.
✓ B.The access point will not power on.
C.The switch port will be damaged.
D.The access point will power on and function normally.
Why B: The existing switch supports only 802.3af (PoE), which provides a maximum of 15.4 watts per port. The access point requires 25 watts, which exceeds the 802.3af power budget. Since the switch cannot deliver the required power, the access point will not power on. This is a strict power negotiation failure under IEEE 802.3 standards.
Last reviewed: Jun 11, 2026
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