220-1101 Question 78
Single answerChannelsA technician is configuring a dual-band wireless router in a small office. Employees report that the 2.4 GHz Wi-Fi connection is slow and drops frequently during the day, especially when nearby offices are busy. The technician uses a Wi-Fi analyzer and sees several neighboring networks heavily using channels 1 and 6. Which action should the technician take FIRST to reduce interference on the 2.4 GHz network?
- A
Change the 2.4 GHz network to channel 11
- B
Increase the channel width to 40 MHz on 2.4 GHz
- C
Move all users to the 5 GHz band and disable 2.4 GHz
- D
Change the SSID name so client devices reconnect cleanly
Show answer and explanation
Correct answer: A
Explanation
This question tests practical understanding of wireless channels in a real support scenario. On CompTIA A+ Core 1, candidates are expected to recognize that the 2.4 GHz spectrum has limited non-overlapping channels, with 1, 6, and 11 being the standard choices in many deployments. When nearby networks are already concentrated on channels 1 and 6, switching to channel 11 is the most effective first troubleshooting step. This aligns with common wireless best practices from enterprise and SMB Wi-Fi design guidance: avoid overlapping channels, prefer 20 MHz width on 2.4 GHz, and use 5 GHz where possible for higher throughput and lower interference. However, 5 GHz migration is not always the first or only fix because device support and coverage needs must be considered.
- A. Correct.
Correct. In the 2.4 GHz band, the non-overlapping channels commonly used are 1, 6, and 11 in many regions. If channels 1 and 6 are congested, moving the WLAN to channel 11 is the best first step to reduce co-channel and adjacent-channel interference while preserving compatibility for devices that rely on 2.4 GHz.
- B. Incorrect.
Incorrect. Increasing channel width to 40 MHz on 2.4 GHz usually makes interference worse, not better, because it consumes more of the already limited spectrum. Best practice for crowded 2.4 GHz environments is typically to use 20 MHz channels.
- C. Incorrect.
Incorrect. Moving users to 5 GHz can help performance, but disabling 2.4 GHz is not the best first action in this scenario. Many offices still have legacy or low-power devices that depend on 2.4 GHz for range or compatibility. The immediate issue described is channel congestion on 2.4 GHz, so selecting a less congested channel is the most appropriate first step.
- D. Incorrect.
Incorrect. Changing the SSID does not address RF interference or channel contention. Although reconnecting clients may occur after an SSID change, the underlying problem of overlapping wireless traffic on crowded channels would remain.