- A
Bluetooth interference
Why wrong: Bluetooth also uses 2.4 GHz but typically causes less sustained disruption than a cordless phone base station.
- B
Microwave oven interference
Why wrong: Microwaves cause intermittent interference when in use, not constant; the issue is persistent.
- C
Co-channel interference from a neighboring Wi-Fi network
Why wrong: This could affect both bands, but the 5 GHz band is fine, pointing to a specific 2.4 GHz interferer.
- D
RF interference from the cordless phone base
Cordless phones operating at 2.4 GHz cause continuous interference, explaining the poor performance on that band.
Question 640 of 1,020
Cordless Phone Interference on 2.4 GHz Wi-Fi: Causes and Solutions
This 220-1201 practice question tests your understanding of wireless networking technologies. 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 a home network where the 5 GHz band works fine, but the 2.4 GHz band is extremely slow and drops connections. The router is placed near a cordless phone base station. Which type of interference is most likely occurring?
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.
Quick Answer
The answer is RF interference from the cordless phone base. This is correct because cordless phones commonly operate in the 2.4 GHz ISM band, the same frequency range used by Wi-Fi, creating co-channel interference that degrades signal quality and throughput. Since the 5 GHz band operates on a different frequency, it remains unaffected, which is why the technician sees the problem isolated to the 2.4 GHz band. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of how non-Wi-Fi devices can cause cordless phone interference on 2.4 GHz Wi-Fi, often appearing as a troubleshooting question where you must identify the source of intermittent drops or slow speeds. A common trap is assuming the issue is distance or obstructions, but the key clue is the router’s proximity to the phone base station. For a memory tip, think “2.4 GHz is the crowded band—phones, microwaves, and Bluetooth all share the space, so if 5 GHz is fine, suspect a 2.4 GHz neighbor.”
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
✓
RF interference from the cordless phone base
The 2.4 GHz band is shared by many consumer devices, including cordless phones that operate in the 2.4 GHz ISM band. The proximity of the router to the cordless phone base station causes RF interference, which degrades the 2.4 GHz signal, leading to slow speeds and dropped connections, while the 5 GHz band remains unaffected because it operates on a different frequency range.
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.
- ✗
Bluetooth interference
Why it's wrong here
Bluetooth also uses 2.4 GHz but typically causes less sustained disruption than a cordless phone base station.
- ✗
Microwave oven interference
Why it's wrong here
Microwaves cause intermittent interference when in use, not constant; the issue is persistent.
- ✗
Co-channel interference from a neighboring Wi-Fi network
Why it's wrong here
This could affect both bands, but the 5 GHz band is fine, pointing to a specific 2.4 GHz interferer.
- ✓
RF interference from the cordless phone base
Why this is correct
Cordless phones operating at 2.4 GHz cause continuous interference, explaining the poor performance on that band.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
This question tests the candidate's ability to distinguish between common 2.4 GHz interference sources. The trap is to assume that any 2.4 GHz device (like Bluetooth or a microwave) causes similar interference, but the specific symptoms of persistent, severe degradation due to a nearby cordless phone base station point to intentional RF interference from a device that operates continuously on the same frequency band.
Detailed technical explanation
How to think about this question
Cordless phones using DECT 6.0 technology operate in the 1.9 GHz band, but older 2.4 GHz cordless phones (often analog or digital spread spectrum) directly share the same unlicensed ISM band as Wi-Fi. The base station transmits continuously, creating a constant noise floor that can overwhelm Wi-Fi receivers, especially on channels 1, 6, or 11, which are commonly used. In real-world troubleshooting, a spectrum analyzer would show a wide, flat noise signature from the phone base, distinct from the narrower peaks of Wi-Fi signals.
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
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.
- →
Wireless Networking Technologies — study guide chapter
Learn the concepts, then practise the questions
- →
Wireless Networking Technologies practice questions
Targeted practice on this topic area only
- →
All 220-1201 questions
1,020 questions across all exam domains
- →
CompTIA A+ Core 1 220-1201 study guide
Full concept coverage aligned to exam objectives
- →
220-1201 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related 220-1201 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Mobile Device Hardware Servicing practice questions
Practise 220-1201 questions linked to Mobile Device Hardware Servicing.
Mobile Device Connection Methods practice questions
Practise 220-1201 questions linked to Mobile Device Connection Methods.
Mobile Device Accessories practice questions
Practise 220-1201 questions linked to Mobile Device Accessories.
Mobile Device Network Connectivity practice questions
Practise 220-1201 questions linked to Mobile Device Network Connectivity.
Mobile Device Application Support practice questions
Practise 220-1201 questions linked to Mobile Device Application Support.
Network Protocols practice questions
Practise 220-1201 questions linked to Network Protocols.
TCP & UDP Ports practice questions
Practise 220-1201 questions linked to TCP & UDP Ports.
Wireless Networking Technologies practice questions
Practise 220-1201 questions linked to Wireless Networking Technologies.
Network Services practice questions
Practise 220-1201 questions linked to Network Services.
Network Configuration Concepts practice questions
Practise 220-1201 questions linked to Network Configuration Concepts.
Common Networking Hardware practice questions
Practise 220-1201 questions linked to Common Networking Hardware.
IP Addressing practice questions
Practise 220-1201 questions linked to IP Addressing.
Practice this exam
Start a free 220-1201 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this 220-1201 question test?
Wireless Networking Technologies — This question tests Wireless Networking Technologies — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: RF interference from the cordless phone base — The 2.4 GHz band is shared by many consumer devices, including cordless phones that operate in the 2.4 GHz ISM band. The proximity of the router to the cordless phone base station causes RF interference, which degrades the 2.4 GHz signal, leading to slow speeds and dropped connections, while the 5 GHz band remains unaffected because it operates on a different frequency range.
What should I do if I get this 220-1201 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.
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 →
Keep practising
More 220-1201 practice questions
- During a network cable installation, a technician needs to verify that a newly run Cat6 cable is properly terminated and…
- A user connects a 4K monitor to their laptop using a USB-C port. The monitor is detected, but the resolution is stuck at…
- A technician is troubleshooting a laptop that will not charge. The battery is removable, and the power adapter works on…
- A customer brings in a smartphone with a broken charging port. They want the port replaced. During disassembly, the tech…
- A user reports that their laptop's keyboard types random characters when certain keys are pressed. The laptop has not be…
- A technician is troubleshooting a laptop that shuts down randomly after a few minutes of use. The fan is spinning, and t…
Last reviewed: Jul 4, 2026
This 220-1201 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 220-1201 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.