CWNP CWNA-109 Exam Dumps & Practice Test Questions
Question 1:
You are utilizing a tool that visually displays signal strength from nearby access points, showing available SSIDs and their corresponding security configurations. It allows filtering by frequency band (2.4 GHz or 5 GHz) but offers no additional features.
What type of tool is this?
A. WLAN Scanner
B. Wireless Site Survey Tool
C. Network Protocol Analyzer
D. Radio Spectrum Analyzer
Answer: A
Explanation:
The tool described in the question is a WLAN Scanner. A WLAN scanner is specifically designed to detect nearby wireless networks and display details such as signal strength, available SSIDs (Service Set Identifiers), security configurations, and often provides filtering options such as by frequency band (2.4 GHz or 5 GHz). However, it typically lacks the additional in-depth features that a site survey tool or spectrum analyzer might offer, such as mapping coverage areas or analyzing interference patterns.
Here’s why the other options are not correct:
B. Wireless Site Survey Tool typically offers more advanced features than a WLAN scanner. It can perform detailed surveys, including signal strength mapping, interference analysis, and the creation of coverage heatmaps. This tool is used to plan or optimize a network, which is beyond the basic scanning and filtering functionalities described in the question.
C. Network Protocol Analyzer (such as Wireshark) is used for capturing and analyzing data packets on a network. It allows you to observe various protocol exchanges between devices, but it does not focus on displaying signal strength or SSID details from access points. A protocol analyzer provides detailed packet-level data, which is not the function described in the question.
D. Radio Spectrum Analyzer is used to detect and analyze electromagnetic spectrum activity, focusing on identifying interference sources, including non-Wi-Fi signals that may affect wireless performance. While it provides valuable insights into radio frequency conditions, it does not focus on displaying SSIDs, security configurations, or filtering by frequency band like a WLAN scanner does.
Therefore, A (WLAN Scanner) is the correct answer because it best matches the tool description.
Question 2:
While troubleshooting a WLAN, you suspect a hidden node issue. What pattern should you identify in a protocol analyzer to confirm this?
A. Frames where the retry bit is not set
B. Frames sent by the AP that do not receive acknowledgments
C. Frames marked with a hidden node (HN) flag
D. Multiple clients retransmitting frames with elevated retry counts
Answer: D
Explanation:
A hidden node issue occurs when a client station (STA) is unable to detect other stations within range of the access point (AP) because of physical obstacles or distance, leading to transmission collisions and poor performance. To identify a hidden node problem using a protocol analyzer, the key pattern you would observe is multiple clients retransmitting frames with elevated retry counts.
Here’s why this is the correct pattern:
D. Multiple clients retransmitting frames with elevated retry counts is a clear indication of hidden node issues. When a client station cannot hear other stations, it may transmit data that is not received by the access point or other stations. As a result, the frame will be retransmitted multiple times, increasing the retry count. This is one of the most common indicators of hidden node problems in wireless networks, where clients unknowingly interfere with each other.
Let’s look at the other options:
A. Frames where the retry bit is not set is not indicative of a hidden node issue. In fact, the retry bit is typically set when a frame is retransmitted. If the retry bit is not set, it generally indicates that the frame was transmitted successfully without the need for retransmission, which does not point to a hidden node problem.
B. Frames sent by the AP that do not receive acknowledgments may seem related to hidden nodes, but this behavior can also result from other issues like interference, signal degradation, or misconfigurations. The hidden node issue is more specifically identified by retransmissions with elevated retry counts rather than just missing acknowledgments.
C. Frames marked with a hidden node (HN) flag is not a standard feature in wireless protocol analyzers. While certain diagnostic tools might provide information about potential hidden node issues, there is no specific "hidden node flag" in standard frame headers to mark these frames. Identifying hidden node issues requires analyzing the behavior of retransmissions and retries rather than relying on a flag.
Thus, D (Multiple clients retransmitting frames with elevated retry counts) is the most accurate pattern to identify a hidden node problem. It reflects the inability of clients to successfully communicate due to the hidden node issue, leading to retransmissions and higher retry counts.
Question 3:
Which of the following best defines Equivalent Isotropically Radiated Power (EIRP)?
A. Radio output power after subtracting cable losses
B. Peak RF power emitted by the antenna in its strongest direction
C. Power delivered from the transmission line to the antenna
D. Radio's output power into the RF feed line
Answer: A
Explanation:
Equivalent Isotropically Radiated Power (EIRP) is a measure of the effective power radiated by an antenna. It is the calculated power emitted by the antenna, assuming that it radiates equally in all directions (isotropically), but adjusted to account for the gain of the antenna and losses in the system (such as from cables). Specifically, EIRP is the output power of the transmitter adjusted for cable losses and multiplied by the antenna's gain. This provides a measure of the actual radiated power, factoring in both the transmitter power and the efficiency of the antenna.
Here’s why the other options are incorrect:
B. Peak RF power emitted by the antenna in its strongest direction refers to antenna gain, not EIRP. While the antenna’s directionality and gain impact the overall radiated power, EIRP accounts for the total power emitted, including losses in the system, not just the peak in one direction.
C. Power delivered from the transmission line to the antenna is describing the power at the antenna (before it is radiated), not EIRP. EIRP factors in the radiated power after antenna gain and cable losses.
D. Radio's output power into the RF feed line refers to the transmitter’s power output, not considering losses or antenna gain, which makes it different from EIRP. EIRP incorporates both of those factors to give a more accurate measure of the effective radiated power.
Thus, A (Radio output power after subtracting cable losses) is the best definition of EIRP, as it accounts for the radiated power adjusted for losses and antenna gain.
Question 4:
Which statement correctly describes an 802.11 wireless bridge?
A. It must be deployed where no interference exists on the channel between the endpoints.
B. It supports MIMO only while operating in the 5 GHz band.
C. It operates exclusively on 2.4 GHz using single-stream transmissions.
D. It requires a usable SNR on both ends to sustain bi-directional throughput.
Answer: D
Explanation:
An 802.11 wireless bridge is a networking device used to connect two separate network segments via wireless technology, typically over long distances. The bridge operates in point-to-point mode, transmitting and receiving data between the two endpoints, and it requires a usable Signal-to-Noise Ratio (SNR) on both ends for effective communication.
Here's why D is correct:
D. It requires a usable SNR on both ends to sustain bi-directional throughput is true. For the wireless bridge to function correctly, the signal-to-noise ratio (SNR) must be high enough on both ends of the bridge to ensure reliable communication. A high SNR indicates that the signal strength is much greater than the noise, allowing for effective and stable data transmission. Without adequate SNR, the throughput would be significantly reduced, and the communication link could be unreliable or unstable.
Let’s review why the other options are incorrect:
A. It must be deployed where no interference exists on the channel between the endpoints is not necessarily true. While interference should be minimized for optimal performance, wireless bridges can still work in environments with some interference, although performance may degrade. A proper channel selection and adequate SNR are more critical than complete absence of interference.
B. It supports MIMO only while operating in the 5 GHz band is incorrect. While MIMO (Multiple Input Multiple Output) is a feature that enhances wireless throughput and is more commonly used in the 5 GHz band, it is not restricted to it. MIMO can also work in the 2.4 GHz band in many 802.11n and later devices. Therefore, a wireless bridge can support MIMO on both 2.4 GHz and 5 GHz, depending on the device.
C. It operates exclusively on 2.4 GHz using single-stream transmissions is incorrect. Wireless bridges typically operate on either 2.4 GHz or 5 GHz, and many modern wireless bridges support multiple streams of data (multi-stream MIMO) to improve throughput. Restricting the bridge to single-stream transmission on only the 2.4 GHz band is a limitation, not a standard requirement for 802.11 wireless bridges.
Thus, D (It requires a usable SNR on both ends to sustain bi-directional throughput) is the correct statement because reliable communication through a wireless bridge depends on an adequate signal-to-noise ratio at both ends.
Question 5:
Which WLAN client authentication method, referenced in the 802.11-2016 and 802.11-2020 standards, is considered highly secure?
A. WEP
B. SSL
C. 802.1X with EAP
D. IPSec
Answer: C
Explanation:
The 802.1X with EAP (Extensible Authentication Protocol) method is considered highly secure for WLAN client authentication. This is a robust method commonly used in enterprise-level wireless networks to authenticate clients. 802.1X provides port-based network access control, which means it requires the client to authenticate before accessing the network. The authentication process typically involves a RADIUS (Remote Authentication Dial-In User Service) server to validate user credentials and can be used with multiple EAP methods (such as EAP-TLS, EAP-TTLS, and PEAP), which offer additional layers of security.
The other options are less secure or do not directly apply to WLAN client authentication in the same way:
A. WEP (Wired Equivalent Privacy) is an outdated and insecure protocol that was originally designed to provide security for WLANs. However, it uses weak encryption (RC4) and is highly vulnerable to attacks such as cracking and replay attacks. Due to its inherent weaknesses, WEP is no longer considered secure and is not recommended for use in modern wireless networks.
B. SSL (Secure Sockets Layer) is a cryptographic protocol used for securing communications over networks. While SSL provides security for data transmission, it is not directly involved in WLAN client authentication. SSL is primarily used for securing web traffic (e.g., HTTPS), not for authenticating wireless clients.
D. IPSec (Internet Protocol Security) is a suite of protocols used to secure IP communications by authenticating and encrypting each IP packet in a communication session. While IPSec can be used for securing VPN connections, it is not specifically an authentication method for WLAN clients in the context of the 802.11 standards.
Therefore, C (802.1X with EAP) is the correct answer as it is a highly secure and widely adopted method for WLAN client authentication, referenced in both the 802.11-2016 and 802.11-2020 standards.
Question 6:
Which frame type is utilized to reserve the wireless medium prior to sending high data rate frames that some devices in the network may not understand?
A. PS-Poll
B. Beacon
C. Authentication
D. Request to Send (RTS)
Answer: D
Explanation:
The Request to Send (RTS) frame is part of the RTS/CTS (Request to Send/Clear to Send) handshake protocol used in wireless networks to avoid collisions when devices are transmitting high data rate frames. The RTS frame is sent by a device to request the use of the wireless medium. It helps to reserve the medium for data transmission and ensures that no other devices interfere with the communication, which is especially important when sending large frames that other devices might not understand or handle properly. This mechanism is useful in environments where hidden node issues might occur or when high data rates are being transmitted.
Here’s why the other options are incorrect:
A. PS-Poll (Power Save Poll) is a frame type used by a client device to request data from the access point when it is in power-saving mode. It is not related to reserving the medium for high data rate transmissions. PS-Poll is used for energy-efficient communication and does not help in medium reservation.
B. Beacon frames are broadcast by the access point at regular intervals to announce the presence of the network and provide essential information, such as the SSID and supported data rates. While important for network discovery and management, beacon frames do not serve the purpose of reserving the medium for data transmission.
C. Authentication frames are used during the initial stages of the connection process to authenticate a client to the access point. This is part of the 802.11 association process and has no role in reserving the wireless medium for transmission.
Thus, D (Request to Send - RTS) is the correct answer because it is specifically designed to reserve the wireless medium before sending high data rate frames, ensuring proper communication and preventing potential collisions in the network.
Question 7:
When antenna gain is measured in dBi, it is being compared to which type of theoretical antenna?
A. Human-like radiator
B. Standard dipole antenna
C. Ideal isotropic radiator
D. Directional end-fire antenna
Answer: C
Explanation:
When antenna gain is measured in dBi (decibels relative to an isotropic radiator), it is being compared to an ideal isotropic radiator. An isotropic radiator is a theoretical antenna that radiates power equally in all directions, providing a uniform, spherical radiation pattern. The term "dBi" reflects the relative gain of an actual antenna compared to this theoretical, perfect radiator. Antennas with higher dBi values are more directional, meaning they concentrate their energy in a specific direction rather than radiating it uniformly.
Let's review why the other options are incorrect:
A. Human-like radiator is not a standard reference in antenna gain measurement. Antenna gain is typically compared to ideal theoretical models like isotropic or dipole radiators, not to a human-like radiator.
B. Standard dipole antenna is another common reference for antenna gain measurement, but it is expressed as dBd (decibels relative to a dipole antenna). The term "dBi" specifically compares gain to an isotropic radiator, not a dipole.
D. Directional end-fire antenna refers to a specific type of directional antenna, but it is not the reference used in dBi measurement. The end-fire antenna focuses energy in a specific direction, but again, the theoretical reference for dBi is the isotropic radiator, not a directional type like the end-fire antenna.
Therefore, C (Ideal isotropic radiator) is the correct answer because antenna gain in dBi is always compared to the gain of an ideal isotropic radiator, which radiates energy equally in all directions.
Question 8:
What antenna property typically decreases when replacing it with a similar model that has greater passive gain?
A. Wireless coverage range
B. Beamwidth
C. Active output gain
D. Sensitivity to incoming signals
Answer: B
Explanation:
When replacing an antenna with one that has greater passive gain, the beamwidth of the antenna typically decreases. Passive gain refers to the ability of an antenna to focus its radiated power in a specific direction, which enhances the signal strength in that direction. However, as the gain increases (i.e., the antenna becomes more directional), the beamwidth (the width of the antenna’s radiation pattern) becomes narrower. A higher gain antenna focuses energy into a smaller area, leading to a more directional pattern, which reduces the coverage area or beamwidth.
Here’s why the other options are incorrect:
A. Wireless coverage range generally increases with higher gain antennas, as the focused energy in a particular direction can reach farther distances. However, coverage range does not typically decrease just by increasing passive gain—it is more likely to improve, although the area covered may become more concentrated.
C. Active output gain refers to the actual power output of the antenna, and passive gain does not affect the active output gain. Passive gain is a measure of how well the antenna focuses its radiated energy, not how much power it transmits or receives.
D. Sensitivity to incoming signals is usually linked to the receiver sensitivity of the antenna, which is a factor of the antenna's design and the receiver circuit, not passive gain. A higher gain antenna can improve the ability to focus on and receive signals from specific directions, but it does not decrease sensitivity overall—it typically increases it in the direction the antenna is focusing.
Therefore, B (Beamwidth) is the correct answer because, as the passive gain of an antenna increases, its beamwidth becomes narrower, leading to more directional transmission and reception.
Question 9:
During an on-site WLAN survey, which two measurements best determine whether a client device will maintain a reliable connection to a 5 GHz access point? (Choose 2.)
A. RSSI of −75 dBm or higher (closer to 0)
B. Noise Floor no higher than −90 dBm
C. SNR of 25 dB or greater
D. Channel Utilization below 80 percent
E. Signal Quality (SQ) over 90 percent
Answer: C, D
Explanation:
To determine whether a client device will maintain a reliable connection to a 5 GHz access point, certain metrics are essential. The following two measurements are most important for assessing connection quality:
C. SNR of 25 dB or greater is a key indicator of a strong and stable connection. Signal-to-Noise Ratio (SNR) is the difference between the signal strength (RSSI) and the background noise. An SNR of 25 dB or higher indicates that the signal is strong enough to overcome background noise, which is crucial for ensuring reliable communication, especially in higher-frequency bands like 5 GHz, which can be more susceptible to interference.
D. Channel Utilization below 80 percent is another critical metric. Channel Utilization refers to how much of the available bandwidth is being used on the channel. If Channel Utilization exceeds 80 percent, the network could be congested, leading to performance issues such as slower speeds and higher latency. A low channel utilization ensures that there is sufficient bandwidth for the client device to maintain a stable connection.
Let's now discuss why the other options are less critical for this scenario:
A. RSSI of −75 dBm or higher (closer to 0) indicates the signal strength. While this is important, it is not as direct a measure of connection quality as SNR. An RSSI of −75 dBm is generally acceptable, but it needs to be evaluated in context with the noise level, which is why SNR is more directly correlated with a reliable connection.
B. Noise Floor no higher than −90 dBm indicates the level of background noise. While it’s important to have low noise, a noise floor of −90 dBm is not usually a limiting factor unless it's higher. SNR and channel utilization provide more actionable insights into connection reliability.
E. Signal Quality (SQ) over 90 percent refers to a subjective measure of signal quality. It can be influenced by factors like interference and attenuation but doesn’t provide as detailed or direct information as SNR or channel utilization in predicting connection reliability.
Thus, the two best measurements to determine connection reliability for a 5 GHz access point are C (SNR of 25 dB or greater) and D (Channel Utilization below 80 percent).
Question 10:
Which two IEEE 802.11 frame types are used to establish a secure, authenticated connection between a client and an access point in a WPA2-Enterprise network? (Choose 2.)
A. Probe Request / Probe Response frames
B. Authentication frames (Open System)
C. Association Request / Association Response frames
D. EAPOL (Extensible Authentication Protocol over LAN) key frames
E. Beacon frames advertising RSN information elements
Answer: D, E
Explanation:
In a WPA2-Enterprise network, securing the connection between a client and access point involves a multi-step authentication process. Two important IEEE 802.11 frame types are involved in establishing this secure, authenticated connection:
D. EAPOL (Extensible Authentication Protocol over LAN) key frames are critical in the WPA2-Enterprise authentication process. EAPOL is used to carry the Extensible Authentication Protocol (EAP) messages during the authentication process. The EAPOL key frames are specifically used to exchange encryption keys between the client and the access point after the authentication server has verified the client’s credentials. These keys are essential for encrypting the data traffic between the client and the access point, ensuring the security of the connection.
E. Beacon frames advertising RSN (Robust Security Network) information elements are broadcast by the access point and contain key information about the network’s security configuration, including support for WPA2 and the encryption algorithms used. These frames allow the client to determine whether the network is secure and, if so, what type of security protocol (like WPA2) is being used. The RSN information in the beacon frames is a foundational step for the client to understand the required security settings for establishing a secure connection.
Let’s review why the other options are not as relevant for WPA2-Enterprise authentication:
A. Probe Request / Probe Response frames are used during the initial process of discovering available networks. These frames are part of the passive scanning or active scanning process, where the client searches for available access points. While they help in discovering the network, they are not directly involved in the authentication or key exchange process for WPA2-Enterprise security.
B. Authentication frames (Open System) are part of the initial connection process but are used primarily in Open System Authentication, which is typically seen in WPA or WEP networks. In WPA2-Enterprise, the EAP authentication process (carried over EAPOL frames) replaces the simple open system authentication frames.
C. Association Request / Association Response frames are used in the process of associating a client device with the access point after the authentication has been completed. These frames carry the parameters for the connection (like supported rates, capabilities, etc.), but they do not directly handle the security or key exchange process in WPA2-Enterprise.
Therefore, the two correct frame types involved in establishing a secure, authenticated connection in WPA2-Enterprise are D (EAPOL key frames) and E (Beacon frames advertising RSN information elements).
