The correct answer is adjacent channel interference from access points on overlapping channels. This is the most likely cause because even with strong signal strength, overlapping channels in the 2.4 GHz band—such as channels 1, 2, 3, 4, and 5 all overlapping with channel 1—force devices to contend for airtime and trigger excessive retransmissions, degrading performance without any co-channel collision. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to distinguish between adjacent-channel interference and co-channel interference; a common trap is assuming strong signal means no interference, but overlapping channels create hidden contention. Remember the memory tip: “Overlap equals chaos—stick to 1, 6, 11 to keep it clean.”
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. 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 technician is troubleshooting intermittent wireless connectivity in a conference room. A site survey shows strong signal strength but many nearby access points are using channels that overlap with the channel used by the conference room AP. Which of the following is the most likely cause of the issue?
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
✓
Adjacent channel interference from access points on overlapping channels.
The site survey shows strong signal strength but many nearby access points are using channels that overlap with the channel used by the conference room AP. This directly indicates adjacent-channel interference (ACI), where overlapping channels (e.g., channels 1, 2, 3, 4, and 5 all overlap with channel 1 in the 2.4 GHz band) cause contention and retransmissions, degrading performance even with strong signal. ACI is the most likely cause because the overlapping channels create co-existence issues without being on the exact same channel.
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.
✗
Multipath interference from reflective surfaces.
Why it's wrong here
Multipath interference can cause signal degradation, but the given scenario points to overlapping channels as the cause.
✗
Co-channel interference from access points on the same channel.
Why it's wrong here
Co-channel interference occurs when APs use the exact same channel, not overlapping ones.
✓
Adjacent channel interference from access points on overlapping channels.
Why this is correct
Overlapping channels cause adjacent channel interference, reducing throughput and causing intermittent connectivity.
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.
✗
Signal attenuation due to distance from the AP.
Why it's wrong here
The site survey shows strong signal strength, so attenuation is not the issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between co-channel interference (same channel) and adjacent-channel interference (overlapping channels), and the trap here is that candidates confuse 'overlapping channels' with 'same channel,' incorrectly selecting co-channel interference instead of adjacent-channel interference.
Trap categories for this question
Command / output trap
The site survey shows strong signal strength, so attenuation is not the issue.
Scenario analysis trap
Multipath interference can cause signal degradation, but the given scenario points to overlapping channels as the cause.
Detailed technical explanation
How to think about this question
In the 2.4 GHz ISM band, 802.11 channels are only 22 MHz wide with 5 MHz spacing, meaning channels 1, 6, and 11 are the only non-overlapping channels in most regulatory domains. Adjacent-channel interference occurs when two APs use channels that partially overlap (e.g., channel 1 and channel 3), causing the receiver to decode energy from the overlapping portion as noise, increasing the error rate and triggering retransmissions. Tools like Ekahau or NetSpot can visualize this overlap, and the fix often involves reconfiguring APs to use only channels 1, 6, or 11 with proper cell planning.
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 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.
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: Adjacent channel interference from access points on overlapping channels. — The site survey shows strong signal strength but many nearby access points are using channels that overlap with the channel used by the conference room AP. This directly indicates adjacent-channel interference (ACI), where overlapping channels (e.g., channels 1, 2, 3, 4, and 5 all overlap with channel 1 in the 2.4 GHz band) cause contention and retransmissions, degrading performance even with strong signal. ACI is the most likely cause because the overlapping channels create co-existence issues without being on the exact same channel.
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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