220-1101 Question 75
Single answer2.4GHzA technician is troubleshooting slow and unreliable Wi-Fi for users in a small office. The wireless router is using the 2.4 GHz band, and nearby businesses also have many Wi-Fi networks. Users report frequent disconnects and low throughput, especially during the day. After confirming signal strength is adequate, which action should the technician take FIRST to reduce channel interference on the 2.4 GHz network?
- A
Change the wireless channel to 1, 6, or 11 after checking which of those channels is least congested
- B
Increase the channel width from 20 MHz to 40 MHz to provide more bandwidth on 2.4 GHz
- C
Lower the WPA2 encryption level to reduce overhead and improve signal quality
- D
Disable DHCP on the router so clients can maintain more stable wireless connections
Show answer and explanation
Correct answer: A
Explanation
This scenario focuses on a common real-world 2.4 GHz issue: interference in a crowded wireless environment. When signal strength is acceptable but users still experience poor performance, channel congestion is a likely cause. On 2.4 GHz, overlapping channels can interfere with each other, so technicians should typically select one of the non-overlapping channels: 1, 6, or 11, based on a site survey or Wi-Fi analyzer results. Industry best practices and vendor guidance from wireless manufacturers commonly recommend 20 MHz channel width on 2.4 GHz in dense deployments, because 40 MHz often increases overlap and reduces overall performance. Security settings such as WPA2 and network services such as DHCP do not resolve RF interference problems. This aligns with CompTIA A+ Core 1 expectations for basic wireless troubleshooting and understanding of 2.4 GHz channel behavior.
- A. Correct.
Correct. In the 2.4 GHz band, the standard non-overlapping channels commonly used are 1, 6, and 11 in regions such as North America. In congested environments, selecting the least utilized of these channels is a best practice to reduce co-channel and adjacent-channel interference. Since signal strength has already been verified, channel selection is an appropriate first troubleshooting step.
- B. Incorrect.
Incorrect. Although wider channels can increase theoretical throughput, using 40 MHz in the crowded 2.4 GHz band usually makes interference worse because it consumes more spectrum and overlaps more heavily with neighboring networks. Best practice for 2.4 GHz in busy environments is typically to use 20 MHz channels.
- C. Incorrect.
Incorrect. WPA2 encryption does not address RF interference or channel congestion. Lowering security would create unnecessary risk and would not solve the root cause of disconnects caused by competing 2.4 GHz networks. This option reflects the misconception that performance problems are often caused by encryption rather than radio interference.
- D. Incorrect.
Incorrect. DHCP manages IP address assignment, not wireless radio performance. Disabling DHCP would likely create client connectivity issues unless static addressing were configured everywhere, but it would not reduce 2.4 GHz interference or improve RF stability.