CWS CWS Wireless Client Devices 3 — Questions and Answers
Question 1: In 802.11 networks, which mechanism do clients use to avoid collisions before transmitting data?
- CSMA/CD
- CSMA/CA with random backoff (Correct answer)
- Token passing
- Polling by the AP
Correct answer: CSMA/CA with random backoff
CSMA/CA with random backoff (EDCA/DCF) causes clients to wait a random period after detecting a clear channel before transmitting.
Question 2: Which 802.11 security protocol uses SAE (Simultaneous Authentication of Equals) to replace the PSK handshake?
- WPA2-Personal
- WPA3-Personal (Correct answer)
- WPA2-Enterprise
- WEP
Correct answer: WPA3-Personal
WPA3-Personal replaces PSK with SAE, providing forward secrecy and resistance to offline dictionary attacks.
Question 3: A client reports slow Wi-Fi despite strong signal. A spectrum analyzer shows high non-Wi-Fi interference at 2.4 GHz. What is the best client-side workaround?
- Reduce the client transmit power
- Switch the client to the 5 GHz band (Correct answer)
- Enable WMM on the client
- Increase the RTS threshold on the client
Correct answer: Switch the client to the 5 GHz band
Moving the client to 5 GHz avoids the congested 2.4 GHz band where microwave ovens and Bluetooth create interference.
Question 4: What is the maximum number of spatial streams supported by an 802.11ac Wave 2 (Wi-Fi 5) client device?
- 2
- 4 (Correct answer)
- 8
- 16
Correct answer: 4
802.11ac Wave 2 supports up to 4 spatial streams for SU-MIMO, while MU-MIMO supports up to 4 simultaneous clients.
Question 5: Which EAP method uses a TLS tunnel to protect inner authentication and only requires a server-side certificate?
- EAP-TLS
- PEAP (Correct answer)
- EAP-MD5
- LEAP
Correct answer: PEAP
PEAP creates an encrypted TLS tunnel using only a server certificate, then authenticates the client via an inner method like MS-CHAPv2.
Question 6: A user's laptop shows a 'limited connectivity' warning after joining a secured Wi-Fi network. Which troubleshooting step should be performed first?
- Replace the wireless NIC driver
- Verify the DHCP server is reachable and has available leases (Correct answer)
- Disable the firewall on the laptop
- Change the Wi-Fi channel on the AP
Correct answer: Verify the DHCP server is reachable and has available leases
Limited connectivity typically indicates the device associated but failed to get an IP, making DHCP the first thing to verify.
Question 7: What is the role of the PMK (Pairwise Master Key) in 802.11 security?
- It encrypts management frames
- It is the top-level key from which the PTK is derived during the 4-Way Handshake (Correct answer)
- It is used to encrypt broadcast traffic
- It authenticates the RADIUS server
Correct answer: It is the top-level key from which the PTK is derived during the 4-Way Handshake
The PMK is derived from the PSK or from EAP authentication and serves as the root keying material for the 4-Way Handshake.
CWS CWS Wireless Client Devices 3
In 802.11 networks, which mechanism do clients use to avoid collisions before transmitting data?