Which of the following statements about wireless channel interference are correct? (Select all that apply.)
Correct Answer: A,B,C
Detailed Explanation: Wireless networks rely on radio frequencies to transmit data. However, these frequencies can be affected by interference from various sources, leading to degraded performance and reduced throughput. Understanding channel interference, particularly in the popular 2.4 GHz and 5 GHz frequency bands, is vital for designing and troubleshooting wireless networks. A. 2.4 GHz Non-Overlapping Channels: In the 2.4 GHz frequency band, the available channels are spaced closely together, meaning that many channels overlap. In most regulatory domains (such as in North America), only channels 1, 6, and 11 are considered non-overlapping. Using these channels helps ensure that adjacent networks or devices do not interfere with one another, improving overall performance and reducing collision rates. B. 5 GHz Band Advantages: The 5 GHz band offers a larger number of channels, many of which do not overlap. This allows network administrators to plan channel assignments more effectively, reducing interference even in high-density environments. The increased number of channels in the 5 GHz spectrum makes it an attractive option for enterprise wireless deployments, where managing interference is critical to maintaining high throughput and reliability. C. Sources of Interference: Wireless interference is not limited to other Wi-Fi devices. Non-Wi-Fi sources—such as microwave ovens, cordless phones, Bluetooth devices, and even baby monitors—can emit signals in the 2.4 GHz band, causing significant interference. These devices may operate on frequencies that overlap with Wi-Fi channels, thereby impacting performance. Awareness of these potential sources of interference is important when planning the physical placement of wireless access points and when selecting channels to minimize disruption. D. Impact on Throughput (Incorrect): Contrary to Option D, wireless interference has a direct and often detrimental impact on network throughput. Interference can lead to packet loss, increased latency, and reduced overall performance. When signals are disrupted or collided, the devices must retransmit data, which decreases effective throughput. Proper channel planning and interference mitigation techniques (such as using the 5 GHz band and non-overlapping channels) are necessary to maintain optimal wireless performance. Importance in Network Design: Designing a robust wireless network requires careful attention to channel planning and interference management. Administrators must consider both the number of available channels and the potential sources of interference when deploying access points. Tools like spectrum analyzers and wireless site surveys are used to assess the radio frequency environment and optimize channel selection. Conclusion: In summary, in the 2.4 GHz band, channels 1, 6, and 11 are the only non-overlapping options (Option A), and the 5 GHz band provides many non-overlapping channels that can reduce interference (Option B). Moreover, interference from non-Wi-Fi sources (Option C) is a real and common challenge in wireless deployments. The notion that interference does not affect throughput (Option D) is incorrect, as interference directly impacts network performance. These insights are fundamental for both troubleshooting and designing efficient wireless networks.
This CCNA practice question helps students prepare for Cisco networking certification exams by testing knowledge of network fundamentals, routing, switching, and network security concepts.