The answer is to change some APs to use channels 40, 44, or 48 to reduce co-channel interference. This is correct because co-channel interference on 5 GHz occurs when multiple access points operate on the same channel, such as channel 36, forcing them to share the same medium and contend for airtime, which causes intermittent disconnections and slow performance for 5 GHz clients while leaving 2.4 GHz users unaffected. On the CCNA 200-301 v2 exam, this scenario tests your understanding of RF channel planning and the 802.11ac Wave 2 requirement for non-overlapping 20 MHz channels; a common trap is assuming that 5 GHz automatically avoids interference, but dense AP deployments still create CCI if channels aren’t spread. Remember the memory tip: “Don’t crowd channel 36—spread across 40, 44, and 48 to keep the 5 GHz airtime clean.”
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. 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 network administrator is troubleshooting a wireless connectivity issue in a large office. Users on the 5 GHz band report intermittent disconnections and slow performance, while 2.4 GHz clients are unaffected. The office uses a Cisco 9800 WLC with APs that support 802.11ac Wave 2. The administrator checks the WLC's RF profile and notices a high number of channel utilization reports on channel 36. What is the most likely cause of the problem?
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.
Why wrong: DFS channels are used to avoid radar, but the exhibit shows no radar events and the problem is co-channel interference, not DFS avoidance.
B
Change some APs to use channels 40, 44, or 48 to reduce co-channel interference.
Co-channel interference occurs when multiple APs use the same frequency channel, causing contention. Changing some APs to non-overlapping channels reduces this.
C
Increase the channel width to 160 MHz to improve throughput.
Why wrong: Wider channels increase throughput but also increase interference and are more susceptible to CCI; the problem is channel reuse, not width.
D
Disable the 2.4 GHz radios to force all clients to 5 GHz.
Why wrong: The 2.4 GHz band is not the issue; disabling it would remove a working band and not solve the 5 GHz CCI.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change some APs to use channels 40, 44, or 48 to reduce co-channel interference.
Channel 36 is a 20 MHz channel in the 5 GHz band. When many APs use the same channel (channel 36), they share the same medium, leading to co-channel interference (CCI). This causes intermittent disconnections and slow performance for 5 GHz clients because they must contend for airtime. Spreading APs across non-overlapping channels like 40, 44, or 48 reduces CCI and improves performance.
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.
✗
Enable DFS channels to avoid radar interference.
Why it's wrong here
DFS channels are used to avoid radar, but the exhibit shows no radar events and the problem is co-channel interference, not DFS avoidance.
✓
Change some APs to use channels 40, 44, or 48 to reduce co-channel interference.
Why this is correct
Co-channel interference occurs when multiple APs use the same frequency channel, causing contention. Changing some APs to non-overlapping channels reduces this.
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.
✗
Increase the channel width to 160 MHz to improve throughput.
Why it's wrong here
Wider channels increase throughput but also increase interference and are more susceptible to CCI; the problem is channel reuse, not width.
✗
Disable the 2.4 GHz radios to force all clients to 5 GHz.
Why it's wrong here
The 2.4 GHz band is not the issue; disabling it would remove a working band and not solve the 5 GHz CCI.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Change some APs to use channels 40, 44, or 48 to reduce co-channel interference.Correct answer▾
Why this is correct
Co-channel interference occurs when multiple APs use the same frequency channel, causing contention. Changing some APs to non-overlapping channels reduces this.
✗Enable DFS channels to avoid radar interference.Wrong answer — click to see why▾
Why this is wrong here
DFS channels are used to avoid radar interference, but the problem described is co-channel interference on channel 36, not radar events. The exhibit shows no radar events, so enabling DFS channels would not address the high channel utilization.
Why candidates choose this
Students may confuse DFS with dynamic channel assignment or think that DFS helps with interference in general, but DFS specifically handles radar detection and avoidance, not co-channel interference.
✗Increase the channel width to 160 MHz to improve throughput.Wrong answer — click to see why▾
Why this is wrong here
Increasing channel width to 160 MHz would actually increase the likelihood of co-channel interference because fewer non-overlapping channels are available, and it would not solve the existing high utilization on channel 36.
Why candidates choose this
Students might think wider channels always improve throughput, but in dense environments, wider channels exacerbate interference and are not recommended without proper planning.
✗Disable the 2.4 GHz radios to force all clients to 5 GHz.Wrong answer — click to see why▾
Why this is wrong here
Disabling 2.4 GHz radios would force all clients to 5 GHz, potentially worsening the co-channel interference on channel 36 by adding more clients to an already congested channel. The 2.4 GHz band is not the source of the problem.
Why candidates choose this
Some might think that moving all clients to 5 GHz would improve performance, but without addressing the channel reuse issue, it would only increase congestion on the 5 GHz band.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that DFS channels are the solution for any 5 GHz interference issue, but the trap here is that high channel utilization on a non-DFS channel (36) indicates co-channel interference, not radar avoidance.
Trap categories for this question
Command / output trap
DFS channels are used to avoid radar, but the exhibit shows no radar events and the problem is co-channel interference, not DFS avoidance.
Detailed technical explanation
How to think about this question
In 802.11ac Wave 2, APs can use channel bonding (e.g., 80 MHz) by combining four 20 MHz channels. However, if multiple APs are configured to use the same primary channel (e.g., channel 36) within the same bonding set, they will still contend for the same medium, causing CCI. The Cisco 9800 WLC's RRM (Radio Resource Management) can automatically assign channels to minimize CCI, but if manual configuration or static channel assignments are used, this issue arises. A real-world scenario is a dense office where APs are placed too close together on the same channel, leading to hidden node problems and retransmissions.
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 200-301 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 200-301 question in full detail.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change some APs to use channels 40, 44, or 48 to reduce co-channel interference. — Channel 36 is a 20 MHz channel in the 5 GHz band. When many APs use the same channel (channel 36), they share the same medium, leading to co-channel interference (CCI). This causes intermittent disconnections and slow performance for 5 GHz clients because they must contend for airtime. Spreading APs across non-overlapping channels like 40, 44, or 48 reduces CCI and improves performance.
What should I do if I get this 200-301 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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