- A
Conduct a spectrum analysis to identify sources of interference and reposition APs away from the elevator shafts.
Spectrum analysis reveals non-Wi-Fi interference (e.g., from elevator motors) and guides AP placement to minimize its impact.
- B
Enable frequency hopping on the APs to avoid interference.
Why wrong: 802.11ac does not use frequency hopping; it uses fixed channel widths. This option is not feasible.
- C
Increase the transmit power of the APs in the east wing to improve signal-to-noise ratio.
Why wrong: Higher power does not eliminate interference; it can even cause more co-channel interference and may not address the source.
- D
Deploy additional APs in the elevator area to provide more capacity and redundancy.
Why wrong: More APs can increase contention and co-channel interference if not properly planned; the root cause is likely external interference.
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network security. 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 large hospital uses a wireless LAN (WLAN) for mobile medical devices and staff tablets. Recently, nurses reported intermittent connectivity drops and high retransmission rates specifically in the east wing near the elevator banks. The WLAN is based on 802.11ac in the 5 GHz band. The hospital's IT team has already checked for channel overlap, and the APs are configured to use non-overlapping channels with automatic channel selection. Signal strength in the area is adequate (-65 dBm). However, the retransmission rate spikes during peak hours. Which approach should the network team take FIRST to diagnose and resolve the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
Conduct a spectrum analysis to identify sources of interference and reposition APs away from the elevator shafts.
The symptoms—intermittent connectivity drops and high retransmission rates near elevator banks during peak hours—strongly suggest external RF interference, likely from the elevator motors or other electrical equipment. A spectrum analysis is the correct first step because it can identify non-Wi-Fi interference sources (e.g., microwave ovens, motors, or radar) that cause packet corruption and retransmissions, even when signal strength is adequate and channels are non-overlapping. Repositioning APs away from the elevator shafts after identifying the interference source directly mitigates the physical cause.
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.
- ✓
Conduct a spectrum analysis to identify sources of interference and reposition APs away from the elevator shafts.
Why this is correct
Spectrum analysis reveals non-Wi-Fi interference (e.g., from elevator motors) and guides AP placement to minimize its impact.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Enable frequency hopping on the APs to avoid interference.
Why it's wrong here
802.11ac does not use frequency hopping; it uses fixed channel widths. This option is not feasible.
- ✗
Increase the transmit power of the APs in the east wing to improve signal-to-noise ratio.
Why it's wrong here
Higher power does not eliminate interference; it can even cause more co-channel interference and may not address the source.
- ✗
Deploy additional APs in the elevator area to provide more capacity and redundancy.
Why it's wrong here
More APs can increase contention and co-channel interference if not properly planned; the root cause is likely external interference.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume retransmissions are caused by congestion or weak signal and jump to adding APs or increasing power, but the specific location (elevator banks) and intermittent nature point to external interference, which requires spectrum analysis first.
Detailed technical explanation
How to think about this question
Elevator shafts often contain large metal structures and electrical motors that generate broadband RF noise, particularly in the 5 GHz band, which can cause CRC errors and retransmissions at the MAC layer. A spectrum analyzer (e.g., using a tool like Ekahau or a USB spectrum analyzer) can visualize this noise floor and identify the specific frequency range affected, allowing the network team to either move APs away or select channels that avoid the interference. In 802.11ac, retransmissions are triggered by failed frame checks (FCS errors) or missing ACKs, which are classic signs of interference rather than congestion.
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 security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this CISSP question test?
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Conduct a spectrum analysis to identify sources of interference and reposition APs away from the elevator shafts. — The symptoms—intermittent connectivity drops and high retransmission rates near elevator banks during peak hours—strongly suggest external RF interference, likely from the elevator motors or other electrical equipment. A spectrum analysis is the correct first step because it can identify non-Wi-Fi interference sources (e.g., microwave ovens, motors, or radar) that cause packet corruption and retransmissions, even when signal strength is adequate and channels are non-overlapping. Repositioning APs away from the elevator shafts after identifying the interference source directly mitigates the physical cause.
What should I do if I get this CISSP 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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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 →
Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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