CWS Wireless Security & Troubleshooting Techniques 3 — Questions and Answers
Question 1: Which troubleshooting step BEST isolates whether a wireless performance problem is caused by RF interference versus AP configuration?
- Reboot the AP and test again
- Connect the same client to the AP via Ethernet and compare throughput (Correct answer)
- Change the SSID name
- Disable WPA2 encryption temporarily
Correct answer: Connect the same client to the AP via Ethernet and compare throughput
Comparing wired vs. wireless throughput from the same client and AP location isolates whether the issue is in the RF medium or the AP/network configuration.
Question 2: What does a high 'retry rate' in an AP's statistics indicate?
- Too many client associations
- Poor RF conditions or interference causing frame retransmissions (Correct answer)
- Successful load balancing across APs
- RADIUS server latency
Correct answer: Poor RF conditions or interference causing frame retransmissions
A high retry rate means the AP or client is frequently retransmitting frames, which typically points to RF issues such as low SNR or interference.
Question 3: A WLAN client receives an IP via DHCP but cannot reach the internet. Other wireless clients on the same SSID work fine. What is the FIRST thing to check?
- The client's IP address, subnet mask, default gateway, and DNS settings (Correct answer)
- The AP transmit power level
- The RADIUS server authentication log
- The 802.11 channel plan
Correct answer: The client's IP address, subnet mask, default gateway, and DNS settings
Verifying the client's IP configuration ensures it received correct network parameters; a misconfigured DHCP scope or static IP conflict could affect only that client.
Question 4: Which attack involves the attacker capturing the WPA2 four-way handshake and then running an offline dictionary attack?
- ARP poisoning
- KRACK attack
- PSK brute-force via captured handshake (Correct answer)
- Session hijacking
Correct answer: PSK brute-force via captured handshake
By capturing the four-way handshake, an attacker can test pre-shared key candidates offline without needing to stay on the network.
Question 5: KRACK (Key Reinstallation Attack) targets which phase of the WPA2 connection process?
- EAP identity exchange
- The four-way handshake nonce reinstallation (Correct answer)
- RADIUS Access-Request
- Beacon frame parsing
Correct answer: The four-way handshake nonce reinstallation
KRACK manipulates retransmissions in the four-way handshake to force nonce reuse, weakening the encryption key.
Question 6: A CWS technician needs to verify which channels nearby APs are using to minimize co-channel interference. Which tool is MOST appropriate?
- OTDR (Optical Time Domain Reflectometer)
- Wi-Fi analyzer application or spectrum analyzer (Correct answer)
- Network vulnerability scanner
- SNMP trap receiver
Correct answer: Wi-Fi analyzer application or spectrum analyzer
A Wi-Fi analyzer or spectrum analyzer displays nearby SSIDs, their channels, and signal strengths, enabling channel planning to avoid co-channel interference.
Question 7: What is the purpose of SSID segmentation combined with VLAN tagging in a secure enterprise WLAN?
- To increase AP transmit power per SSID
- To cryptographically isolate traffic between different user groups at Layer 1
- To separate traffic from different user groups into isolated Layer 2 network segments (Correct answer)
- To allow the AP to broadcast on multiple channels simultaneously
Correct answer: To separate traffic from different user groups into isolated Layer 2 network segments
Mapping each SSID to a separate VLAN ensures that employee, guest, and IoT traffic remain isolated at Layer 2, reducing lateral movement risk.
CWS Wireless Security & Troubleshooting Techniques 3
Which troubleshooting step BEST isolates whether a wireless performance problem is caused by RF interference versus AP configuration?