- A
Co-channel interference from neighboring access points
Why wrong: Co-channel interference typically causes poor signal quality and lower throughput, but the problem states signal strength is good. It is less likely when signal is strong unless many APs are on same channel, but the scenario specifically points to physical environment.
- B
Multipath interference caused by signal reflections off metal surfaces
Metal racks cause reflections, leading to multipath. With strong signal but low throughput, multipath is the classic symptom. 802.11ac uses MIMO to mitigate multipath, but severe multipath can still degrade performance.
- C
The encryption method is set to WEP, which limits throughput
Why wrong: WEP security would impact compatibility and security, but it does not directly cause such a drastic drop in throughput. Modern clients usually negotiate higher security, and throughput drops from encryption are minimal.
- D
Too many clients are connected to the same access point
Why wrong: High client count can reduce per-client throughput, but the problem mentions strong signal and low throughput without specifying many users. The environment suggests physical obstacles are more likely.
Quick Answer
The answer is multipath interference caused by signal reflections off metal surfaces. In a warehouse with dense metal racks, 802.11ac signals bounce off these surfaces, creating multiple delayed signal paths that arrive at the receiver at slightly different times. This phenomenon causes phase cancellation and intersymbol interference, which degrades the signal-to-noise ratio and forces the radio to fall back to lower modulation and coding schemes (MCS), drastically reducing throughput even when the received signal strength indicator (RSSI) appears strong. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding that high signal strength does not guarantee high throughput—a common trap where students confuse RSSI with actual data rate. The key is to recognize that multipath interference is the primary culprit in reflective environments like warehouses, not distance or channel congestion. Memory tip: think “metal racks = multiple paths = messy timing,” and remember that strong signal can still mean slow data when reflections cause the waves to fight each other.
N10-009 Network Implementation Practice Question
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 is deploying a wireless network in a warehouse environment with many metal racks. Clients using 802.11ac report strong signal strength but very low throughput. 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 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
Multipath interference caused by signal reflections off metal surfaces
In a warehouse with many metal racks, 802.11ac signals reflect off the metal surfaces, creating multiple signal paths that arrive at the receiver at slightly different times. This multipath interference causes phase cancellation and intersymbol interference, which degrades the signal-to-noise ratio and forces the use of lower modulation and coding schemes (MCS), drastically reducing throughput despite strong RSSI.
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.
- ✗
Co-channel interference from neighboring access points
Why it's wrong here
Co-channel interference typically causes poor signal quality and lower throughput, but the problem states signal strength is good. It is less likely when signal is strong unless many APs are on same channel, but the scenario specifically points to physical environment.
- ✓
Multipath interference caused by signal reflections off metal surfaces
Why this is correct
Metal racks cause reflections, leading to multipath. With strong signal but low throughput, multipath is the classic symptom. 802.11ac uses MIMO to mitigate multipath, but severe multipath can still degrade performance.
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 encryption method is set to WEP, which limits throughput
Why it's wrong here
WEP security would impact compatibility and security, but it does not directly cause such a drastic drop in throughput. Modern clients usually negotiate higher security, and throughput drops from encryption are minimal.
- ✗
Too many clients are connected to the same access point
Why it's wrong here
High client count can reduce per-client throughput, but the problem mentions strong signal and low throughput without specifying many users. The environment suggests physical obstacles are more likely.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'strong signal strength' and assume the issue is at Layer 2 or higher (co-channel interference, encryption, or client count), but the metal racks create a classic multipath scenario where RSSI is high but SNR is low due to phase cancellation.
Trap categories for this question
Scenario analysis trap
Co-channel interference typically causes poor signal quality and lower throughput, but the problem states signal strength is good. It is less likely when signal is strong unless many APs are on same channel, but the scenario specifically points to physical environment.
Detailed technical explanation
How to think about this question
802.11ac uses OFDM and MIMO to achieve high throughput, but multipath can cause frequency-selective fading where subcarriers are nulled. The receiver's equalizer can compensate for some delay spread, but in a highly reflective environment like a metal warehouse, the delay spread exceeds the guard interval (0.4 µs or 0.8 µs), causing intersymbol interference that forces the AP to fall back to lower MCS rates (e.g., from MCS9 to MCS0), reducing throughput from 1.3 Gbps to as low as 6.5 Mbps. Real-world testing often shows that moving a client just a few feet can dramatically improve throughput as the multipath null shifts.
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 network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
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: Multipath interference caused by signal reflections off metal surfaces — In a warehouse with many metal racks, 802.11ac signals reflect off the metal surfaces, creating multiple signal paths that arrive at the receiver at slightly different times. This multipath interference causes phase cancellation and intersymbol interference, which degrades the signal-to-noise ratio and forces the use of lower modulation and coding schemes (MCS), drastically reducing throughput despite strong RSSI.
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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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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