Cisco CCNA Exam: Direct Sequence Spread Spectrum and 2.4-GHz Channel Collision Limitation

Direct Sequence Spread Spectrum Channels for Collision Limitation at 2.4-GHz


Using direct sequence spread spectrum, which three 2.4-GHz channels are used to limit collisions?



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A. B. C. D.


Direct Sequence Spread Spectrum (DSSS) is a method used to spread a signal over a wide frequency band. It involves dividing the data signal into small chunks and then transmitting each chunk over a wider frequency band using a specific code.

In the 2.4 GHz frequency band, DSSS uses 22 MHz wide channels. These channels are spaced 5 MHz apart, with a frequency overlap of 2 MHz. This means that only channels 1, 6, and 11 are non-overlapping channels in the 2.4 GHz frequency band, and these are the channels typically recommended to limit collisions.

Collisions can occur when multiple devices transmit on the same channel at the same time, causing interference and reducing network performance. By using non-overlapping channels, DSSS can help reduce the likelihood of collisions and improve network performance.

Therefore, the correct answer is option C, which lists channels 1, 6, and 11 as the three channels used to limit collisions in the 2.4 GHz frequency band when using DSSS. Options A, B, and D are not correct because they do not include all three of these non-overlapping channels.