CWNA Wireless Network Administrator MCQ 5 — Questions and Answers
Question 1: What is the primary purpose of Dynamic Frequency Selection (DFS) in the 5 GHz band?
- Automatically boost transmit power on congested channels
- Detect radar systems and vacate channels used by them (Correct answer)
- Select the least-congested channel during initial AP boot
- Balance client load across multiple APs
Correct answer: Detect radar systems and vacate channels used by them
DFS is an FCC-mandated mechanism requiring 5 GHz devices to detect military and weather radar signals and switch to a radar-free channel within 10 seconds.
Question 2: A CWNA candidate converts 100 mW to dBm. What is the correct value?
- 10 dBm
- 20 dBm (Correct answer)
- 30 dBm
- 40 dBm
Correct answer: 20 dBm
dBm = 10 × log10(mW/1 mW); 10 × log10(100) = 10 × 2 = 20 dBm.
Question 3: Which 802.11 QoS access category has the highest priority and is intended for voice traffic under WMM?
- AC_BE (Best Effort)
- AC_BK (Background)
- AC_VI (Video)
- AC_VO (Voice) (Correct answer)
Correct answer: AC_VO (Voice)
Under WMM, AC_VO (Voice) has the shortest arbitration inter-frame space and smallest contention window, giving voice traffic the highest channel access priority.
Question 4: What is the function of the RADIUS server in an 802.1X/EAP WLAN deployment?
- Issues 802.11 beacons on behalf of the AP
- Acts as the authentication server that validates client credentials (Correct answer)
- Assigns RF channels to APs dynamically
- Provides DHCP leases to wireless clients
Correct answer: Acts as the authentication server that validates client credentials
In 802.1X, the RADIUS server is the Authentication Server (AS) that validates the client's EAP credentials and communicates results to the authenticator (AP or WLC).
Question 5: An administrator observes that clients near the AP edge are 'sticky' and refuse to roam to a closer AP. Which client-side mechanism is responsible for this behavior?
- AP load balancing blocking the reassociation
- Client-controlled roaming decisions based on its own RSSI threshold (Correct answer)
- 802.11k neighbor reports forcing the client to stay
- WPA2 PMK caching preventing re-authentication
Correct answer: Client-controlled roaming decisions based on its own RSSI threshold
Roaming decisions are made by the client, not the AP; many clients have high RSSI thresholds before they initiate roaming, causing them to stay associated to a distant AP.
Question 6: Which statement best describes Free Space Path Loss (FSPL)?
- Signal loss due to physical obstructions such as walls and floors
- The predictable decrease in signal strength as electromagnetic waves spread over distance in open air (Correct answer)
- Interference caused by adjacent-channel overlap between APs
- Attenuation introduced by the cable between the AP and its antenna
Correct answer: The predictable decrease in signal strength as electromagnetic waves spread over distance in open air
FSPL is the loss of signal strength in a clear line-of-sight path due solely to the spreading of the radio wavefront over distance; it increases with both distance and frequency.
Question 7: A CWNA engineer wants to verify that a newly installed AP's regulatory domain is correctly configured. Which tool or mechanism is most appropriate for this check?
- Ping the AP's default gateway and measure latency
- Review the AP's country/regulatory domain setting in the management interface or CLI (Correct answer)
- Run a passive site survey and count beacons
- Check the cable spec on the PoE switch port
Correct answer: Review the AP's country/regulatory domain setting in the management interface or CLI
The regulatory domain determines which channels and power levels an AP is permitted to use; this is configured in the AP's management system and should be verified there.
CWNA Wireless Network Administrator MCQ 5
What is the primary purpose of Dynamic Frequency Selection (DFS) in the 5 GHz band?