CompTIA Network+ (N10-009)Network TroubleshootingEasy
A technician is troubleshooting poor Wi-Fi performance in a small office. A Wi-Fi analyzer shows three access points operating on channels 3, 7, and 10 in the 2.4GHz band. What is the MOST likely cause of the performance issues?
- AThe access points are using non-overlapping channels
- BThe access points are causing adjacent channel interference
- CThe access points are set to different SSIDs
- DThe access points are transmitting at too low a power level
Show answer & explanationAnswer & explanation
Correct answer: B. The access points are causing adjacent channel interference
In the 2.4GHz band, only channels 1, 6, and 11 are truly non-overlapping. Channels 3, 7, and 10 overlap with neighboring channels, causing adjacent channel interference and degraded performance. The fix is to reconfigure the APs to use 1, 6, or 11.
Why the other options are wrong
- A. These channels are not non-overlapping; only 1, 6, and 11 qualify in 2.4GHz.
- C. Different SSIDs are normal and not a cause of interference.
- D. Low power would reduce range/signal strength but is unrelated to the channel overlap issue described.
2.4GHz Non-Overlapping Channels
In the 2.4GHz Wi-Fi band, only channels 1, 6, and 11 do not overlap with each other, minimizing interference between nearby access points.
- 2.4GHz band spans channels 1-11 (US) with 20MHz width each
- Only 1, 6, 11 avoid overlap
- Using other channels causes adjacent channel interference and throughput loss
Memory trick: Remember '1-6-11' like a stoplight — the only safe channels in 2.4GHz.