This N10-009 practice question tests your understanding of network implementation. 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 needs to power IP phones and wireless access points through the Ethernet cable. Which standard should be supported?
802.3af
802.3af is the IEEE standard for Power over Ethernet, providing up to 15.4W to powered devices.
802.11ac
Why wrong: 802.11ac is a wireless networking standard, not related to power delivery over Ethernet.
802.1X
Why wrong: 802.1X is a port-based authentication standard, not for power delivery.
802.3ab
Why wrong: 802.3ab defines Gigabit Ethernet over twisted-pair copper, not PoE.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
802.3af
The 802.3af standard, also known as Power over Ethernet (PoE), delivers up to 15.4 watts of DC power over twisted-pair Ethernet cabling. This allows devices like IP phones and wireless access points to receive both data and power through a single Ethernet cable, eliminating the need for separate power supplies.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
802.3af
Why this is correct
802.3af is the IEEE standard for Power over Ethernet, providing up to 15.4W to powered devices.
Related concept
Read the scenario before looking for a memorised answer.
802.11ac
Why it's wrong here
802.11ac is a wireless networking standard, not related to power delivery over Ethernet.
802.1X
Why it's wrong here
802.1X is a port-based authentication standard, not for power delivery.
802.3ab
Why it's wrong here
802.3ab defines Gigabit Ethernet over twisted-pair copper, not PoE.
Common exam traps
The trap here is confusing the 802.3 family of wired Ethernet standards (which includes PoE) with the 802.11 family of wireless standards (like 802.11ac), leading candidates to mistakenly select a Wi-Fi standard for a power-over-cable requirement.
Detailed technical explanation
802.3af uses two of the four twisted pairs in a Cat5 or better cable to carry power, either on the data pairs (Alternative A) or the spare pairs (Alternative B). The powered device (PD) negotiates power classification with the power sourcing equipment (PSE) using a detection signature before power is applied, ensuring safe operation. In real-world deployments, 802.3af is often insufficient for high-power devices like pan-tilt-zoom cameras, which may require 802.3at (PoE+) or 802.3bt (PoE++) instead.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
The correct answer is: 802.3af — The 802.3af standard, also known as Power over Ethernet (PoE), delivers up to 15.4 watts of DC power over twisted-pair Ethernet cabling. This allows devices like IP phones and wireless access points to receive both data and power through a single Ethernet cable, eliminating the need for separate power supplies.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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