Certified Wireless Network Administrator (CWNA) Practice Questions
Prepare for CWNA-109 with more than an answer.
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- v1Version 1 223 questions Current
- CWNA-108Legacy Certified Wireless Network Administrator (CWNA) 59 questions Locked
- Exam fee
- $274.99 USD
- Level
- Foundation
- Valid for
- 3 years
Domains covered on the exam 6
- Radio Frequency (RF) Technologies15%
- WLAN Regulations and Standards20%
- WLAN Protocols and Devices20%
- WLAN Network Architecture and Design Concepts15%
- WLAN Network Security10%
- RF Validation and Remediation20%
- 1
The primary cryptographic vulnerability in WPA2-Personal that allows for offline dictionary attacks against the passphrase is known as the KRACK attack.
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Correct answer: B
This statement is false. The vulnerability that allows offline dictionary attacks against WPA2-Personal is inherent in its 4-way handshake, where an attacker can capture the handshake and then try to guess the password offline. The KRACK (Key Reinstallation Attack) is a separate vulnerability that exploits weaknesses in the 4-way handshake to reinstall an already-in-use key, potentially allowing an attacker to decrypt traffic. WPA3's SAE protocol is specifically designed to prevent offline dictionary attacks.
- 2
Which of the following security mechanisms should be avoided in a modern enterprise WLAN due to significant, well-known vulnerabilities? (Select THREE)
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Correct answer: A, C, D
Wired Equivalent Privacy (WEP) is a deprecated security protocol with severe cryptographic flaws that allow it to be cracked in minutes.
Hiding the SSID is a form of security through obscurity that is easily defeated, as the SSID is still transmitted in Probe Request/Response frames. It provides no real security.
The Temporal Key Integrity Protocol (TKIP) was a stop-gap measure and has known vulnerabilities. Modern standards mandate its deprecation in favor of AES-CCMP.
- 3
A hospital is experiencing poor performance on its VoWiFi network used by medical staff. A validation survey shows RSSI values are consistently strong (above -65 dBm), but the SNR is often below 20 dB. A spectrum analysis is performed. What is the most effective first step to remediate the issue?
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Correct answer: B
The combination of strong RSSI and low SNR indicates a high noise floor, which is almost always caused by RF interference. Increasing AP power would raise both the signal and the noise floor for other APs, worsening the problem. The correct approach is to use the spectrum analyzer to identify the signature of the interfering device (e.g., medical equipment, microwaves), locate it, and then either shield, move, or replace it.
- 4
While troubleshooting a client's slow connection in a crowded office, a protocol analysis reveals an extremely high percentage of frame retries and frequent transmissions of RTS/CTS frames, even for small packets. Which two issues are the most likely causes of these symptoms? (Select TWO)
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Correct answer: A, B
The hidden node problem occurs when two clients can hear the AP, but not each other. They may transmit simultaneously, causing collisions at the AP. This leads to frame corruption, a lack of ACKs, and thus high retry rates. The RTS/CTS mechanism is designed to mitigate this, so its frequent use is a strong indicator.
High levels of RF interference from either Wi-Fi or non-Wi-Fi sources can corrupt frames in transit. When a frame is corrupted, it fails its integrity check at the receiver, an ACK is not sent, and the transmitter must retransmit the frame, leading to a high retry count.
- 5
A network administrator uses a throughput tester like iPerf to measure the performance of a Wi-Fi link. The client's negotiated data rate is 866 Mbps. Which of the following iPerf results would be considered a realistic and acceptable real-world throughput for this link?
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Correct answer: B
Due to the half-duplex nature of Wi-Fi, protocol overhead (preambles, headers, interframe spaces, ACKs), and environmental factors, the actual TCP throughput is typically 40-60% of the negotiated data rate. For an 866 Mbps data rate, a throughput of around 480 Mbps (approx. 55%) is a realistic and healthy result. Results close to the data rate are impossible.
- 6
A network engineer is designing a 1.2 km point-to-point wireless bridge using the 5 GHz band. A building under construction is located directly in the path, 0.5 km from one end. To ensure link reliability, 60% of the first Fresnel zone must remain clear of this obstruction. What is the minimum required height clearance above the building?
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Correct answer: B
The formula for the radius of the first Fresnel zone is r = 17.32 * sqrt((d1d2)/(fD)), where d1 and d2 are distances from the ends, D is total distance, and f is frequency in GHz. At the building location (d1=0.5, d2=0.7, D=1.2, f=5), the radius is ~8.15 meters. 60% clearance requires 0.60 * 8.15 = ~4.9 meters. The other options result from common calculation errors.
- 7
A WLAN deployed in a historic library with dense stone walls and ornate metal fixtures is experiencing inconsistent connectivity and low throughput, despite adequate signal strength readings. Which RF behaviors are the most likely primary contributors to this issue? (Select TWO)
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Correct answer: A, B
Metal fixtures cause significant RF reflection, leading to severe multipath where signals arrive at the receiver at different times, causing inter-symbol interference and degrading performance.
Dense stone walls are a primary source of absorption, which converts RF energy into heat, severely attenuating the signal and reducing coverage range.
- 8
A technician installs an access point using a 10-meter coaxial cable with a 75-ohm impedance rating instead of the specified 50-ohm cable. Which measurement at the AP's radio port would most directly indicate this installation error?
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Correct answer: C
An impedance mismatch between the 50-ohm system (AP and antenna) and the 75-ohm cable causes signal reflections. VSWR is the direct measurement of this reflection and the resulting standing waves. A high VSWR indicates a significant impedance mismatch, which can damage the transmitter and severely degrade performance.
- 9
True or False: A vertical polarization mismatch of 90 degrees between a transmitter and receiver antenna can theoretically result in a signal loss of over 20 dB.
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Correct answer: A
Polarization refers to the orientation of the electric field of the RF wave. If the transmitting and receiving antennas have a 90-degree polarization mismatch (e.g., one is vertically polarized and the other is horizontally polarized), the receiving antenna will be unable to efficiently capture the signal energy. This cross-polarization can result in significant signal loss, often exceeding 20 dB, effectively nullifying the link.
- 10
An administrator in an FCC regulatory domain deploys a Wi-Fi 6E network in an office building adjacent to a naval base. The APs operating on U-NII-6 and U-NII-8 channels are frequently and unpredictably changing channels, causing brief client disconnects. What is the most likely cause of this behavior?
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Correct answer: B
U-NII-6 (6.425-6.525 GHz) and U-NII-8 (6.875-7.125 GHz) bands in the 6 GHz spectrum are subject to contention-based protocols to protect incumbent users, which functions similarly to DFS. The naval base is a likely source of incumbent radar signals. When an AP detects these signals, it must vacate the channel immediately and move to a different one, causing the observed disconnects.
