[Q51-Q75] 合格させるCWNA-109試験一発合格保証100%カバー率でリアル試験問題 [2024年07月]

合格させるCWNA-109試験一発合格保証100%カバー率でリアル試験問題 [2024年07月]

有効なCWNA-109テスト解答CWNP CWNA-109試験PDF問題を試そう

質問 # 51
When an ACK frame is not received by the transmitting STA, what is assumed?

• A. The receiver processed the frame, but did not respond with an ACK frame because 802.11w is enabled
• B. The frame was correctly delivered
• C. The receiver is offline
• D. The frame was not delivered and must be retransmitted

正解：D

解説：
An ACK (Acknowledgement) frame is a short control frame that is sent by the receiver of a data or management frame to confirm that the frame was received correctly. The ACK frame is sent after a SIFS (Short Interframe Space) interval, which is the shortest time gap between frames in 802.11. If the transmitter does not receive an ACK frame within a specified time, it assumes that the frame was not delivered and must be retransmitted. This is part of the 802.11 reliability mechanism that ensures reliable data delivery over an unreliable wireless medium . References: [CWNA-109 Study Guide], Chapter 5: IEEE 802.11 Medium Access, page 209; [CWNA-109Study Guide], Chapter 5: IEEE 802.11 Medium Access, page 203.

質問 # 52
What wireless networking term describes the increase of RF energy in an intentional direction with the use of an antenna?

• A. Passive Gain
• B. Beam Digression
• C. Active Amplification
• D. Directed Radiation

正解：A

解説：
Passive Gain is the increase of RF energy in an intentional direction with the use of an antenna. It is achieved by focusing the same amount of power into a smaller area, resulting in a higher power density and a stronger signal. Passive Gain does not require any additional power or amplification, but rather depends on the antenna's physical characteristics, such as size, shape, and orientation. Passive Gain is also expressed in decibels (dB) and is related to the antenna's beamwidth and directivity. References: 1, Chapter 2, page 63; 2, Section 2.3

質問 # 53
You have been tasked with creating a wireless link between two buildings on a single campus. The link must support at least 150 Mbps data rates. What kind of WLAN technology role should you deploy?

• A. Access BSS
• B. WPAN
• C. Wireless bridging
• D. IBSS

正解：C

解説：
https://www.wlanmall.com/what-is-a-wireless-bridge/
Wireless bridging is a WLAN technology role that allows two or more networks to be connected wirelessly over a distance. A wireless bridge consists of two or more APs that are configured to operate in bridge mode and use directional antennas to establish a point-to-point or point-to-multipoint link. Wireless bridging can support high data rates and is suitable for scenarios where running cables is impractical or expensive. To create a wireless link between two buildings on a single campus that supports at least 150 Mbps data rates, wireless bridging is an appropriate solution678. References: CWNA-109 Study Guide, Chapter 6: Wireless LAN Devices and Topologies, page 271; CWNA-109Study Guide, Chapter 6: Wireless LAN Devices and Topologies, page 265; Wi-Fi Wireless Bridging Explained.

質問 # 54
Your manager asked you to locate a solution that allows for centralized monitoring of WLAN performance over time. He wants a single pane of glass for administration and monitoring of the solution. What do you recommend?

• A. Overlay WLAN monitoring solution
• B. Laptop-based protocol analyzers
• C. AP-based spectrum analysis
• D. Laptop-based spectrum analyzers

正解：A

解説：
The solution that you recommend is an Overlay WLAN monitoring solution. An Overlay WLAN monitoring solution is a system that uses dedicated sensors or probes to monitor the WLAN performance over time. The sensors are deployed throughout the WLAN coverage area and collect data on various metrics such as signal strength, noise level, channel utilization, interference, throughput, latency, packet loss, and QoS. The sensors send the data to a centralized server or appliance that analyzes the data and provides a single pane of glass for administration and monitoring of the solution. An Overlay WLAN monitoring solution can help to detect and troubleshoot WLAN issues, optimize WLAN performance, and generate reports and alerts. References: [CWNP Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 538; [CWNA: Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 508.

質問 # 55
Three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. Assuming no other APs are in the vicinity, is CCI still a possibility in this network and why?

• A. Yes, because channel 11 loops around and causes CCI with channel 1.
• B. No, because CCI only occurs in the 5 GHz frequency band.
• C. No, because the APs are far enough apart that no CCI will occur.
• D. Yes, because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP.

正解：D

解説：
CCI is still a possibility in this network because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP. CCI stands for co-channel interference, which is a type of interference that occurs when two or more devices transmit on the same channel within range of each other. CCI reduces performance and capacity because it causes contention and collisions on the wireless medium, which leads to retransmissions and delays. CCI can be mitigated by increasing physical separation between devices using the same channel or byreducing transmit power levels to limit coverage area. In this scenario, three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. However, this does not prevent CCI from occurring between their client devices that are connected on channel 1. For example, if a client device connected to one of the channel 1 APs sends a frame to another device on the wired network or on another wireless network (such as an Internet server or a VoIP phone), that frame will be heard by both channel 1 APs as well as any other client devices connected to either of them on channel 1. This will cause CCI because these devices will have to wait for the channel to be clear before they can transmit their own frames. The answer that CCI only occurs in the 5 GHz frequency band is incorrect; CCI can occur in any frequency band where devices use the same channel. The answer that channel 11 loops around and causes CCI with channel 1 is also incorrect; channel 11 does not loop around and it operates in a different frequency band than channel 1. References: CWNA-109 Study Guide, Chapter 5:
Radio Frequency Signal and Antenna Concepts, page 147

質問 # 56
You administer a small WLAN with nine access point. As a small business, you do not rum a RADIUS server and use WPA2-Personal for security. Recently, you changed the passphrase for WPA2-personal in all Aps and clients. Several users are now reporting the inability to connect to the network at time and it is constrained to one area of the building. When using scanner, you see that the AP covering that area is online

• A. The AP that covers the problem area requires a firmware update
• B. The AP that covers the problem area has failed
• C. The AP that covers the problem area is improperly configured
• D. The clients are improperly configured

正解：D

解説：
This is because the passphrase for WPA2-Personal is case-sensitive and must match exactly on both the AP and the client. If the passphrase is entered incorrectly on the client, the client will not be able to authenticate with the AP and connect to the network. The AP that covers the problem area is not likely to require a firmware update, fail, or be improperly configured, as it is online and works with other clients that have the correct passphrase. To troubleshoot this issue, you can check the passphrase settings on the clients and make sure they matchwith the AP. You can also try to reconnect the clients to the network or reboot them if necessary. For more information on how to configure WPA2-Personal on your router

質問 # 57
A POE device requires 47 W of power. What POE specification should be used?

• A. 802.3at
• B. 802.3bt
• C. 802.3af
• D. 802. 11at

正解：B

解説：
A POE device that requires 47 W of power should use the 802.3bt specification. This is because 802.3bt is the latest POE standard that supports up to 90 W of power delivery over four pairs of wires in an Ethernet cable.
The previous POE standards, such as 802.3af and 802.3at, only support up to 15.4 W and 30 W of power delivery over two pairs of wires in an Ethernet cable, respectively. Therefore, they are not sufficient for powering a device that requires 47 W of power. The 802.11at specification does not exist; it is a typo or confusion with the 802.3at specification. References: CWNA-109 Study Guide, Chapter 8: Wireless LAN Access Points, page 2431

質問 # 58
What factor is likely to cause the least impact on the application layer throughput of an 802.11n client station in a 2.4 GHz HT BSS?

• A. Implementing Fast BSS Transition (FT) for roaming
• B. Increasing or decreasing the number of spatial streams in use by the client station and AP
• C. RF interference from more than 10 nearby Bluetooth transmitters
• D. Implementation of several other clients in the same BSS using 802.11g radios

正解：A

解説：
Implementing Fast BSS Transition (FT) for roaming is likely to cause the least impact on the application layer throughput of an 802.11n client station in a 2.4 GHz HT BSS. FT is a feature that allows a client station to quickly switch from one AP to another within the same ESS (Extended Service Set) without having to re-authenticate and re-associate with each AP. This reduces the latency and packet loss that may occur during roaming, thus improving the user experience and maintaining the application layer throughput. FT is defined in the IEEE 802.11r amendment and is also known as Fast Roaming or Fast Secure Roaming. References: , Chapter 9, page 367; , Section 6.3

質問 # 59
ABC Company is planning a point-to-multipoint outdoor bridge deployment with standalone (autonomous)
802.11 bridge units. 802.1X/EAP will be used for bridge authentication. A Linux-based RADIUS server will be used for authentication. What device in the bridge implementation acts as the 802.1X Authenticator?

• A. All non-root bridges
• B. The Ethernet switch
• C. The root bridge
• D. The RADIUS server

正解：C

解説：
The device in the bridge implementation that acts as the 802.1X Authenticator is the root bridge. The root bridge is the bridge that connects to the wired network and acts as the central point for all other bridges in the point-to-multipoint topology. The root bridge authenticates the non-root bridges using 802.1X/EAP and forwards their authentication requests to the RADIUS server. The non-root bridges act as the 802.1X Supplicants and use EAP methods such as EAP-TLS or EAP-PEAP to authenticate with the root bridge. References: [CWNP Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 459; [Cisco Aironet Wireless Bridges FAQ], question 29.

質問 # 60
What statement about 802.11 WLAN performance is true?

• A. To get the best performance out of an AP, you should disable data rates of 72 Mbps and lower
• B. WLANs perform better as more wireless clients connect with each AP
• C. In modem networks, both centralized and distributed data forwarding work well for most standard office deployments
• D. In most WLANs, no special skill or tuning is required to get peak performance

正解：C

解説：
The statement that in modern networks, both centralized and distributed data forwarding work well for most standard office deployments is true about WLAN performance. Data forwarding refers to how wireless frames are transmitted from wireless clients to wired networks or vice versa through wireless access points (APs).
Centralized data forwarding means that all wireless frames are sent to a central controller or gateway before being forwarded to their destinations. Distributed data forwarding means that wireless frames are forwarded directly by the APs to their destinations without going through a central controller or gateway. Both methods have their advantages and disadvantages, depending on the network size, topology, traffic pattern, security, and management requirements. However, in modern networks, both methods can achieve high performance and scalability for most standard office deployments, as they can leverage advanced features such as fast roaming, load balancing, quality of service, and encryption. The other statements about WLAN performance are false. In most WLANs, special skill or tuning is required to get peak performance, such as selecting the appropriate channel, power, data rate, and antenna settings. WLANs perform worse as more wireless clients connect with each AP, as they cause more contention and interference on the wireless medium. To get the best performance out of an AP, you should not disable data rates of 72 Mbps and lower, as they are needed for backward compatibility and range extension. References: CWNA-109 Study Guide, Chapter 9: Wireless LAN Architecture, page 2811

質問 # 61
The center frequency of channel 1 in the 2.4 GHz band is 2.412 GHz (2412 MHz). What is the center frequency of channel 4?

• A. 2.413
• B. 2.417
• C. 2.422
• D. 2.427

正解：D

解説：
The center frequency of channel 4 in the 2.4 GHz band is 2.427 GHz (2427 MHz). The center frequency of a channel is the midpoint of its frequency range, where the signal strength is highest and most concentrated. The center frequency of channel 1 in the 2.4 GHz band is 2.412 GHz (2412 MHz), as given in the question. The center frequency of each subsequent channel is obtained by adding 5 MHz to the previous channel's center frequency, since the channels are spaced 5 MHz apart from each other in this band. Therefore, to find the center frequency of channel 4, we need to add 15 MHz (5 MHz x 3) to the center frequency of channel 1:
2.412 GHz + 0.015 GHz = 2.427 GHz
Alternatively, we can use a formula to calculate the center frequency of any channel in the 2.4 GHz band:
Center frequency (GHz) = 2.407 + (0.005 x Channel number)
Using this formula for channel 4, we get:
Center frequency (GHz) = 2.407 + (0.005 x 4)
Center frequency (GHz) = 2.407 + 0.02
Center frequency (GHz) = 2.427 References: 1, Chapter 3, page 85; 2, Section 3.2

質問 # 62
You are troubleshooting a problem with interference from a non-802.11 device. Given that the device is not a WLAN device, you cannot use a protocol analyzer and have chosen to use a spectrum analyzer. You want to view the signal from the interfering device over time to see the activity that is generating.
What common spectrum analyzer view should you use for this analysis?

• A. Waterfall/Spectrogram
• B. Real-time FFT
• C. APs
• D. Clients

正解：A

解説：
The common spectrum analyzer view that you should use for this analysis is the Waterfall/Spectrogram view.
The Waterfall/Spectrogram view shows the signal from the interfering device over time on a three-dimensional graph. The x-axis represents frequency, the y-axis represents time, and the z-axis represents amplitude or power. The color of each pixel indicates the signal strength at a given frequency and time. The Waterfall/Spectrogram view can help you identify the characteristics of the interference source, such as its frequency range, duty cycle, modulation type, and pattern. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 524; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 494.

質問 # 63
During a post-implementation survey, you have detected a non-802.11 wireless device transmitting in the area used by handheld 802.11g scanners. What is the most important factor in determining the impact of this non-802.11 device?

• A. Channel occupied
• B. Airtime utilization
• C. Protocols utilized
• D. Receive sensitivity

正解：B

解説：
Airtime Utilization is a per-channel statistic that defines what percentage of the channel is currently being used, and what percentage is therefore free. Airtime usage can come from: Data traffic to and from client devices. Interference from WiFi and non-WiFi sources. Management overhead from APs and client devices.https://wyebot.com/2019/06/06/understanding-airtime-utilization/

質問 # 64
An RF signal sometimes bends as it passes through some material other than free space. What is the term that describes this behavior?

• A. Refraction
• B. Reflection
• C. Warping
• D. Scattering

正解：A

解説：
Refraction is the bending of an RF signal as it passes through a medium with a different density than free space. This can cause the signal to change its direction and speed, which can affect the accuracy and reliability of wireless communication. Refraction is influenced by factors such as temperature, humidity, and atmospheric pressure12. References: CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 72; CWNA-109Study Guide, Chapter 2: Radio Frequency Fundamentals, page 67.

質問 # 65
What is the final step in an effective troubleshooting process?

• A. Notify the users of problem resolution
• B. Document the results
• C. Verify the solution
• D. Disable the WLAN

正解：B

解説：
The final step in an effective troubleshooting process is to document the results. Documentation is essential for keeping track of the problem history, the actions taken, the solutions implemented, and the outcomes achieved.
Documentation can also help to prevent future problems, improve best practices, and provide feedback for improvement. Documentation should include relevant information such as problem description, symptoms, root cause analysis, resolution steps, verification methods, and lessons learned. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 513; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 483.

質問 # 66
An RF signal sometimes bends as it passes through a material rather than around an obstacle. What is the RF behavior that this statement best describes?

• A. Refraction
• B. Reflection
• C. Diffraction
• D. Scattering

正解：A

解説：
Refraction is the bending of an RF signal as it passes through a material of different density. Refraction can cause the signal to change its direction and angle of arrival. For example, when a light beam passes from air to water, it bends because of the difference in the refractive index of the two mediums. Similarly, when an RF signal passes from one medium to another, such as from air to glass, it can bend due to the change in the dielectric constant of the materials12. References: 1:CWNA-109Official Study Guide, page 67 2: Refraction

質問 # 67
What is required when operating 802.11ax APS in the 6 GHz band using passphrase-based authentication?
* VHT PHY

• A. CCMP
• B. HT PHY
• C. SAE

正解：A

解説：
SAE (Simultaneous Authentication of Equals) is required when operating 802.11ax APs in the 6 GHz band using passphrase-based authentication. SAE is a secure and robust authentication method that is defined in the IEEE 802.11s amendment and is also known as WPA3-Personal or WPA3-SAE. SAE is based on a cryptographic technique called Dragonfly Key Exchange, which allows two parties to establish a shared secret key using a passphrase, without revealing the passphrase or the key to an eavesdropper or an attacker. SAE also provides forward secrecy, which means that if the passphrase or the key is compromised in the future, it does not affect the security of past communications.
SAE is required when operating 802.11ax APs in the 6 GHz band using passphrase-based authentication because of the new regulations and standards that apply to this band. The 6 GHz band is a new frequency band that was opened for unlicensed use by the FCC and other regulatory bodies in 2020. The 6 GHz band offers more spectrum and less interference than the existing 2.4 GHz and 5 GHz bands, which can enable higher performance and efficiency for Wi-Fi devices. However, the 6 GHz band also has some restrictions and requirements that are different from the other bands, such as:
* The 6 GHz band is divided into two sub-bands: U-NII-5 (5925-6425 MHz) and U-NII-7 (6525-6875 MHz). The U-NII-5 sub-band is subject to DFS (Dynamic Frequency Selection) rules, which require Wi-Fi devices to monitor and avoid using channels that are occupied by radar systems or other primary users. The U-NII-7 sub-band is not subject to DFS rules, but it has a lower maximum transmit power limit than the U-NII-5 sub-band.
* The Wi-Fi devices that operate in the 6 GHz band are called 6E devices, which stands for Extended Spectrum. 6E devices must support 802.11ax technology, which is also known as Wi-Fi 6 or High Efficiency (HE). 802.11ax is a new standard that improves the performance and efficiency of Wi-Fi networks by using features such as OFDMA (Orthogonal Frequency Division Multiple Access), MU-MIMO (Multi-User Multiple Input Multiple Output), BSS Coloring, TWT (Target Wake Time), and HE PHY and MAC enhancements.
* The 6E devices that operate in the 6 GHz band must also support WPA3 security, which is a new security protocol that replaces WPA2 and provides stronger encryption and authentication for Wi-Fi networks. WPA3 has two modes: WPA3-Personal and WPA3-Enterprise. WPA3-Personal uses SAE as its authentication method, which requires a passphrase to establish a secure connection between two devices. WPA3-Enterprise uses EAP (Extensible Authentication Protocol) as its authentication method, which requires a certificate or a credential to authenticate with a server.
Therefore, SAE is required when operating 802.11ax APs in the 6 GHz band using passphrase-based authentication because it is part of WPA3-Personal security, which is mandatory for 6E devices in this band.
References: , Chapter 3, page 120; , Section 3.2
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質問 # 68
What primary metric of scanning can stations use to select the best AP for connectivity to the desired BSS?

• A. Throughput speed in Mbps.
• B. Signal strength of AP beacons received.
• C. FCS errors in frames transmitted to and from the AP.
• D. PING latency when testing against an Internet server.

正解：B

解説：
When a station scans for available wireless networks, it listens for beacon frames sent by APs. A beacon frame contains information about the BSS, such as SSID, supported rates, channel, security, etc. The station also measures the signal strength of the beacon frames, which indicates how well the station can communicate with the AP. The signal strength is usually expressed in dBm or RSSI units. The higher the signal strength, the better the connection quality and performance. Therefore, the station can use the signal strength of AP beacons as the primary metric to select the best AP for connectivity to the desired BSS12. References: CWNA-109 Study Guide, Chapter 6: Wireless LAN Devices and Topologies, page 249; CWNA-109Study Guide, Chapter
6: Wireless LAN Devices and Topologies, page 243.

質問 # 69
What authentication method is referenced in the 802.11-2016 and 802.11-2020 specifications and is recommended for robust WI-AN client security?

• A. WEP
• B. 802.1X/EAP
• C. IPSec
• D. SSL

正解：B

解説：
The authentication method that is referenced in the 802.11-2016 and 802.11-2020 specifications and is recommended for robust WLAN client security is 802.1X/EAP. 802.1X/EAP stands for IEEE 802.1X Port-Based Network Access Control with Extensible Authentication Protocol and is a framework that provides strong authentication and dynamic encryption key generation for WLAN clients. 802.1X/EAP involves three parties: the supplicant (the client), the authenticator (the AP or the controller), and the authentication server (usually a RADIUS server). The supplicant sends its credentials (such as username and password, certificate, or token) to the authenticator, which forwards them to the authentication server. The authentication server verifies the credentials and sends a response to the authenticator, which grants or denies access to the supplicant. The authentication server also generates a master key that is used to derive encryption keys for the data frames between the supplicant and the authenticator. 802.1X/EAP supports various EAP methods that offer different levels of security and flexibility, such as EAP-TLS, EAP-PEAP, EAP-TTLS, EAP-FAST, and EAP-SIM. SSL, IPSec, and WEP are not authentication methods, but rather encryption or security protocols that are not specific to WLANs or referenced in the 802.11 specifications. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 299; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 289.

質問 # 70
What factor does not influence the distance at which an RF signal can be effectively received?

• A. Receiving station's output power
• B. Free Space Path Loss
• C. Transmitting station's output power
• D. Receiving station's radio sensitivity

正解：A

解説：
In wireless communication, several factors influence the effective reception of RF signals, including the receiving station's radio sensitivity, the transmitting station's output power, and free space path loss. However, the receiving station's output power does not influence the distance at which an RF signal can be effectively received. The key factors that impact signal reception distance are:
* Receiving Station's Radio Sensitivity: This refers to the lowest signal strength at which the receiver can process a signal with an acceptableerror rate. Higher sensitivity allows for better reception at greater distances.
* Transmitting Station's Output Power: This is the power with which a transmitter sends out a signal.
Higher output power can extend the range of transmission, making it easier for distant receivers to detect the signal.
* Free Space Path Loss (FSPL): FSPL represents the attenuation of radio energy as it travels through free space. It increases with distance and frequency, reducing the signal strength as the distance from the transmitter increases.
The output power of the receiving station is related to how strong a signal it sends out, not how well it can receive or process incoming signals. Therefore, it does not affect the reception distance of incoming RF signals.
References:
* CWNA Certified Wireless Network Administrator Official Study Guide: Exam PW0-105, by David D.
Coleman and David A. Westcott.
* RF fundamentals and RF design considerations in wireless communication systems.

質問 # 71
You are troubleshooting a client issue on a Windows laptop. The laptop can see and connect to 2.4 GHz APs, but is does not even see 5 GHz APs. While evaluating the issue, you determine that this problem is happening for all of the laptops of this model in the organization. Several other tablets connect on channel 48 and channel
52 in the same work areas. What is the likely problem?

• A. The clients are configured to use WPA and 5 GHz channels only support WPA2.
• B. The access points are configured to disallow 5 GHz.
• C. The antennas in the laptop have insufficient gain to detect the 5 GHz signals.
• D. The client drivers are faulty and should be upgraded.

正解：D

解説：
The client drivers are faulty and should be upgraded is the likely problem for the laptop that can see and connect to 2.4 GHz APs, but does not even see 5 GHz APs. The client drivers are the software components that enable the wireless adapter of the laptop to communicate with the operating system and the network. The client drivers are responsible for scanning the available wireless channels, detecting and connecting to the access points, negotiating the security and data rate parameters, and transmitting and receiving data frames. If the client drivers are faulty, outdated, or incompatible, they may cause various issues with the wireless performance and functionality, such as low data rates, poor signal strength, frequent disconnections, or inability to see or connect to certain access points or channels.
One of the possible causes of faulty client drivers is that they do not support or recognize some of the features or standards of the 802.11ac technology, such as wider channel bandwidths, higher modulation schemes, or DFS (Dynamic Frequency Selection) channels. This could explain why the laptop can see and connect to 2.4 GHz APs, but not 5 GHz APs, as 802.11ac operates only in the 5 GHz band and uses channels that are wider (up to 160 MHz) and higher (up to channel 165) than those used by previous standards. Moreover, some of the
5 GHz channels are subject to DFS rules, which require the access points and client stations to monitor and avoid using channels that are occupied by radar systems or other primary users. If the client drivers do not support or comply with DFS rules, they may not be able to see or connect to access points that use DFS channels.
To solve this problem, the client drivers should be upgraded to the latest version that supports and is compatible with 802.11ac features and standards. This can be done by downloading and installing the updated driver software from the manufacturer's website or using a device manager tool. Upgrading the client drivers may also improve other aspects of wireless performance and functionality, such as data rates, signal strength, security, and stability. References: 1, Chapter 12, page 493; 2, Section 8.1

質問 # 72
You are deploying a WLAN monitoring solution that utilizes distributed sensor devices. Where should sensors be deployed for best results? Choose the single best answer.

• A. Every 5 meters and alongside each AP
• B. Above the plenum on each floor
• C. In critical areas where WLAN performance must be high
• D. In switching closets

正解：C

解説：
Sensors should be deployed in critical areas where WLAN performance must be high for best results when using a WLAN monitoring solution that utilizes distributed sensor devices. A WLAN monitoring solution is a system that collects, analyzes, and reports on the status and performance of a WLAN. A WLAN monitoring solution can use different methods to gather data from the WLAN, such as embedded software agents, external hardware probes, or distributed sensor devices. Distributed sensor devices are dedicated devices that are deployed throughout the WLAN coverage area to monitor the wireless traffic and environment. Distributed sensor devices can perform various functions, such as scanning the spectrum, capturing wireless frames, measuring signal quality, detecting rogue access points, testing connectivity, and generating alerts. Distributed sensor devices can provide more accurate and comprehensive data than other methods, but they also require more planning and deployment costs. Therefore, it is important to deploy sensors strategically in critical areas where WLAN performance must be high, such as high-density zones, high-priority applications, or high-security locations. By deploying sensors in critical areas, the WLAN monitoring solution can ensure optimal WLAN performance and reliability in those areas and identify and resolve any issues or problems that may arise. The other options are not the best places to deploy sensors for best results. Deploying sensors in switching closets is not effective because sensors need to be close to the wireless medium to monitor it properly. Deploying sensors every 5 meters and alongside each AP is not efficient because sensors may overlap or interfere with each other and cause unnecessary redundancy or complexity. Deploying sensors above the plenum oneach floor is not practical because sensors may not capture the wireless traffic and environment accurately due to attenuation or reflection from the ceiling materials or objects. References: CWNA-109 Study Guide, Chapter 14: Troubleshooting Wireless LANs, page 4831

質問 # 73
A natural disaster has occurred in a remote area that is approximately 57 miles from the response team headquarters. The response team must implement a local wireless network using 802.11 WLAN access points.
What is the best method, of those listed, for implementation of a network back-haul for communications across the Internet in this scenario?

• A. 802.11 bridging to the response team headquarters
• B. Turn up the output power of the WLAN at the response team headquarters
• C. Cellular/LTE/5G
• D. Temporary wired DSL

正解：C

解説：
Cellular/LTE/5G is the best method for implementing a network backhaul for communications across the Internet in a remote area that is affected by a natural disaster. This is because cellular/LTE/5G networks are wireless and do not depend on physical infrastructure that may be damaged or unavailable in such scenarios.
Cellular/LTE/5G networks also offer high-speed data transmission and wide coverage area, which are essential for emergency response operations. 802.11 bridging to the response team headquarters is not feasible because it requires line-of-sight and has limited range. Turning up the output power of the WLAN at the response team headquarters is not effective because it may cause interference and does not guarantee reliable connectivity. Temporary wired DSL is not practical because it requires installing cables and equipment that may not be available or accessible in a remote area. References: CWNA-109 Study Guide, Chapter 7: Wireless LAN Topologies, page 2031

質問 # 74
A non-802.11 device is suspected of causing interference on the WLAN. You are not certain of the location or type of device. What is the best solution for locating this non-802.11 device?

• A. Laptop-based spectrum analyzer with an omni-directional antenna
• B. Laptop-based spectrum analyzer with a directional antenna
• C. Access point spectrum analyzer
• D. Laptop-based spectrum analyzer with an omni-directional antenna

正解：B

解説：
A laptop-based spectrum analyzer with a directional antenna is the best solution for locating a non-802.11 device that is suspected of causing interference on the WLAN. A spectrum analyzer is a device or a software application that can measure and display the frequency spectrum of electromagnetic signals in a given range.
A spectrum analyzer can show the amplitude, frequency, bandwidth, modulation, and other characteristics of different signals in the spectrum, which can help identify their sources and types. A spectrum analyzer can also detect non-802.11 devices that may cause interference on the WLAN, such as microwave ovens, cordless phones, Bluetooth devices, or radar systems. A laptop-based spectrum analyzer is a software application that runs on a laptop computer and uses an external USB adapter as its RF interface. A laptop-based spectrum analyzer has the advantage of being portable, flexible, and cost-effective compared to a hardware-based spectrum analyzer. A directional antenna is an antenna that radiates or receives RF signals more strongly in one direction than in others. A directional antenna has a high gain and a narrow beamwidth, which means it can focus the RF energy in a specific direction and reduce the interference from other directions. A directional antenna can also increase the range and sensitivity of the RF signal detection. To locate a non-802.11 device that is causing interference on the WLAN, a laptop-based spectrum analyzer with a directional antenna can be used to perform a technique called RF hunting or triangulation. This technique involves pointing the directional antenna in different directions and observing the signal strength and characteristics of the interfering device on the spectrum analyzer. By moving around and changing the direction of the antenna, the location of the interfering device can be estimated based on where the signal strength is highest and most consistent. References: 1, Chapter 7, page 282; 2, Section 4.3

質問 # 75
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