Cisco CCNA (200-301)Network FundamentalsMedium
A wireless engineer is deploying three access points in overlapping coverage areas using the 2.4 GHz band and wants to eliminate co-channel interference. Which set of channels should be assigned to the three APs?
- A3, 6, 9
- B1, 6, 11
- C1, 2, 3
- D1, 5, 9
Show answer & explanationAnswer & explanation
Correct answer: B. 1, 6, 11
In the 2.4 GHz band, only channels 1, 6, and 11 are non-overlapping in most regulatory domains (20 MHz channel width), so assigning these to adjacent APs avoids co-channel and adjacent-channel interference.
Why the other options are wrong
- A. Channels 3, 6, and 9 still overlap partially due to insufficient spacing.
- C. Channels 1, 2, 3 overlap significantly with each other, causing interference.
- D. Channels 1, 5, and 9 are too close together and overlap.
2.4 GHz Non-overlapping Channels
In the 2.4 GHz Wi-Fi band, only three 20 MHz-wide channels (1, 6, 11) do not overlap with each other, making them the standard choice for multi-AP deployments.
- 2.4 GHz band channels are 5 MHz apart but 20-22 MHz wide
- Only 1, 6, 11 avoid overlap
- 5 GHz band has many more non-overlapping channels due to wider spectrum
Memory trick: One, Six, Eleven—the golden trio of clean 2.4 GHz channels.