Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
AP-1 channel: 1 AP-2 channel: 3 AP-3 channel: 6 All three APs cover the same conference area on 2.4 GHz. Transmit power is set to high on all APs.
A wireless site reports that users can connect to the SSID, but performance drops sharply around the conference area whenever the room fills up. Based on the exhibit, what is the most likely cause?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Adjacent-channel interference caused by overlapping 2.4 GHz channels
Channel 3 overlaps with both 1 and 6, which is a common performance problem.
B
Distractor review
A DHCP exhaustion problem on the WLAN
That would prevent some clients from getting addresses, not mainly cause RF performance collapse.
C
Distractor review
An authentication mismatch between the APs and clients
Clients can already connect to the SSID.
D
Distractor review
A missing default route on the wireless controller
That would affect upstream connectivity, not local RF efficiency in this pattern.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is to confuse wireless connectivity issues caused by RF interference with DHCP or authentication problems. Because users can connect to the SSID, candidates might incorrectly suspect DHCP exhaustion or authentication mismatches. However, DHCP exhaustion prevents clients from obtaining IP addresses, not causing throughput drops. Similarly, authentication mismatches prevent connection entirely. Another trap is to blame routing issues like a missing default route on the wireless controller, which affects network reachability but not local wireless signal quality. The key is to recognize that overlapping 2.4 GHz channels cause adjacent-channel interference, which degrades performance even when clients connect successfully.
Technical deep dive
How to think about this question
Adjacent-channel interference occurs when overlapping Wi-Fi channels operate on the same frequency spectrum, causing signal degradation and reduced throughput. In the 2.4 GHz band, channels are spaced 5 MHz apart but each channel occupies about 22 MHz of bandwidth, so overlapping channels interfere with each other. This interference is especially problematic in dense environments like conference rooms where many clients compete for wireless resources. The standard practice in 2.4 GHz wireless deployments is to use only the three non-overlapping channels: 1, 6, and 11. These channels are spaced far enough apart to avoid overlap and minimize interference. Using intermediate channels such as channel 3, which overlaps with both 1 and 6, creates adjacent-channel interference that severely impacts wireless performance. Cisco wireless design guidelines emphasize channel planning to avoid such overlaps. In exam scenarios, candidates often mistake connectivity issues for DHCP or authentication problems, but the ability to connect to the SSID indicates those are not the root cause. The practical impact of adjacent-channel interference is a sharp drop in throughput and increased retransmissions, especially in crowded areas. Understanding channel overlap and proper channel selection is critical for troubleshooting wireless performance problems in Cisco networks.
KKey Concepts to Remember
- The 2.4 GHz Wi-Fi band uses channels spaced 5 MHz apart but each channel occupies about 22 MHz, causing overlapping frequencies between adjacent channels.
- Using overlapping 2.4 GHz channels such as 1, 3, and 6 causes adjacent-channel interference that degrades wireless throughput and increases retransmissions.
- Cisco wireless best practices require using only non-overlapping channels 1, 6, and 11 in the 2.4 GHz band to avoid interference in dense client environments.
- Adjacent-channel interference impacts wireless performance by increasing noise and collisions, especially when many clients connect in the same area.
- Clients connecting successfully to an SSID rules out authentication mismatches as the cause of wireless performance issues.
- DHCP exhaustion affects IP address assignment but does not directly cause RF interference or throughput degradation in wireless networks.
- A missing default route on a wireless controller affects upstream network connectivity but does not cause local wireless RF performance problems.
- Proper channel planning and RF design are essential to prevent adjacent-channel interference and maintain high wireless performance in Cisco WLAN deployments.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
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FAQ
Questions learners often ask
What does this 200-301 question test?
The 2.4 GHz Wi-Fi band uses channels spaced 5 MHz apart but each channel occupies about 22 MHz, causing overlapping frequencies between adjacent channels.
What is the correct answer to this question?
The correct answer is: Adjacent-channel interference caused by overlapping 2.4 GHz channels — The 2.4 GHz radios are using overlapping channels. In 2.4 GHz, the standard non-overlapping channels are 1, 6, and 11 in many regulatory domains. Using channels 1, 3, and 6 creates adjacent-channel interference, which hurts throughput especially in dense client areas.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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