CWNP CWNA-109 Online Practice Questions and Exam Preparation

CWNP CWNA-109 Online Questions & Answers

• Question 41:

  Which one of the following 802.11 PHYs is more likely to be used in an industrial deployment but not likely to be used in standard office deployments?

  A. S1G
  B. VHT
  C. OFDM
  D. HT
  A. S1G

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  Explanation/Reference:

  S1G is one of the 802.11 PHYs that is more likely to be used in an industrial deployment but not likely to be used in standard office deployments. This is because S1G stands for Sub-1 GHz, which means it operates in the frequency bands below 1 GHz, such as 900 MHz and 868 MHz. These bands offer better penetration and range than the higher frequency bands used by other 802.11 PHYs, such as 2.4 GHz and 5 GHz. This makes S1G suitable for industrial applications that require robust and reliable wireless communication in harsh environments, such as factories, warehouses, mines, and smart grids. S1G also supports low-power and low-data-rate devices, such as sensors, actuators, and meters, which are common in industrial Internet of Things (IoT) scenarios. VHT, OFDM, and HT are other 802.11 PHYs that are more commonly used in standard office deployments, as they offer higher data rates and capacity than S1G, but have lower range and penetration. References: CWNA-109 Study Guide, Chapter 3: Radio Frequency Technologies, page 751

• Question 42:

  You have received a report of poor wireless connections on the third floor of a building under your administration. Three individuals have reported the problem. Apparently, the connections are reporting a strong signal, but the users cannot access the Internet. With the problem identified, what is the next logical step in the troubleshooting process?

  A. Verify the solution
  B. Discover the scale of the problem
  C. Perform corrective actions
  D. Create a plan of action or escalate the problem
  B. Discover the scale of the problem

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  Explanation/Reference:

  Discovering the scale of the problem is the next logical step in the troubleshooting process after identifying the problem of poor wireless connections on the third floor of a building under your administration. Troubleshooting is a systematic process of finding and resolving problems or issues in a network or a system. Troubleshooting usually follows a general methodology that consists of several steps or phases, such as: Identifying the problem: This step involves defining and describing the problem clearly and accurately based on the symptoms and evidence observed or reported by users or administrators. For example, in this case, the problem is that three individuals have reported poor wireless connections on the third floor of a building. Discovering the scale of the problem: This step involves determining how widespread and severe the problem is by gathering more information anddata from different sources and perspectives. For example, in this case, this step could involve checking if other users or devices on the third floor or other floors are experiencing similar issues, verifying if there are any changes or updates in the network configuration or environment that could affect the wireless connections, testing if there are any differences in performance or quality between different access points or channels on the third floor, etc. Performing corrective actions: This step involves applying possible solutions or fixes to resolve or mitigate the problem based on logical reasoning and analysis. For example, in this case, this step could involve adjusting the output power or channel assignment of the access points on the third floor, relocating or reorienting some access points or antennas to improve coverage or reduce interference, updating or replacing some faulty or outdated hardware or software components, etc. Verifying the solution: This step involves confirming that the problem is solved or improved by testing and monitoring the network performance and user satisfaction after applying corrective actions. For example, in this case, this step could involve measuring and comparing the signal strength and throughput of wireless connections on the third floor before and after performing corrective actions, asking for feedback from users who reported poor wireless connections to see if their issues are resolved or reduced, etc. Creating a plan of action or escalating the problem: This step involves documenting and reporting the problem and its solution for future reference and improvement purposes. It also involves deciding whether to close or escalate the problem depending on its status and severity. For example, in this case, this step could involve creating a report that summarizes what was done to troubleshoot and fix poor wireless connections on the third floor with relevant data and evidence to support it. It could also involve escalating poor wireless connections to higher- level administrators if they persist or worsen despite performing corrective actions. References: 1, Chapter 12, page

• Question 43:

  What facts are true regarding controllers and APs in a Split MAC architecture?

  A. An IP tunnel is established between the AP and controller for AP management and control functions.
  B. Using centralized data forwarding, APs never tag Ethernet frames with VLAN identifiers or 802.1p CoS.
  C. With 802.1X/EAP security, the AP acts as the supplicant and the controller acts as the authenticator.
  D. Management and data frame types must be processed locally by the AP, while control frame types must be sent to the controller.
  A. An IP tunnel is established between the AP and controller for AP management and control functions.

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  Explanation/Reference:

  The fact that is true regarding controllers and APs in a Split MAC architecture is that an IP tunnel is established between the AP and controller for AP management and control functions. A Split MAC architecture is a WLAN architecture where some of the MAC layer functions are performed by the APs (such as encryption, decryption, and frame acknowledgement) and some are performed by the controllers (such as authentication, association, roaming, and QoS). To communicate with each other, the APs and controllers establish an IP tunnel that carries the management and control frames between them. The IP tunnel can use protocols such as Lightweight Access Point Protocol (LWAPP) or Control And Provisioning of Wireless Access Points (CAPWAP). References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 372; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 362.

• Question 44:

  You are tasked with performing a throughput test on the WLAN. The manager asks that you use open source tools to reduce costs. What open source tool is designed to perform a throughput test?

  A. iPerf
  B. PuTTy
  C. IxChariot
  D. Python
  A. iPerf

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  Explanation/Reference:

  iPerf is an open source tool that is designed to perform a throughput test on the WLAN. iPerf is a cross-platform command-line tool that can measure the bandwidth and quality of network links by generating TCP or UDP traffic between two endpoints.iPerf can run as either a server or a client mode, depending on whether it receives or sends traffic. iPerf can also report various metrics of network performance, such as throughput, jitter, packet loss, delay, and TCP window size. To perform a throughput test on the WLAN using iPerf, one device needs to run iPerf in server mode and another device needs to run iPerf in client mode. The devices need to be connected to the same WLAN network and have their IP addresses configured properly. The device running iPerf in client mode needs to specify the IP address of the device running iPerf in server mode as well as other parameters such as protocol, port number, duration, interval, bandwidth limit, packet size, etc. The device running iPerf in server mode will listen for incoming connections from the client device and send back acknowledgments or responses depending on the protocol used. The device running iPerf in client mode will send traffic to the server device according to the specified parameters and measure the network performance. The device running iPerf in client mode will display the results of the throughput test at the end of the test or at regular intervals during the test. The results can show the average, minimum, maximum, and instantaneous throughput of the network link, as well as other metrics such as jitter, packet loss, delay, and TCP window size. References: 1, Chapter 7, page 287; 2, Section 4.3

• Question 45:

  You are managing a wireless access point in autonomous mode using the Web based interface. You capture traffic during this management task and notice that you can see the HTML code of the Web pages used for access point management. What error in administration could be the cause of this security concern?

  A. IPsec is not in use of the management connection as recommended
  B. A VPN with the AP is not established
  C. WPA2 is disabled on the WLAN
  D. HTTP is in use instead of HTTPS
  D. HTTP is in use instead of HTTPS

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  Explanation/Reference:

  The error in administration that could be the cause of this security concern is that HTTP is in use instead of HTTPS. HTTP is an unencrypted protocol that transfers data in plain text over the network. This means that anyone who captures the traffic can see the HTML code of the Web pages used for access point management, as well as any sensitive information such as passwords or configuration settings. HTTPS is an encrypted protocol that uses SSL/TLS to secure the data transmission between the Web browser and the Web server. HTTPS prevents anyone from snooping on or tampering with the Web traffic. Therefore, HTTPS should always be used for Web based management of wireless access points, especially in autonomous mode where there is no centralized controller to enforce security policies. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 431; [HTTP vs HTTPS: What's The Difference And Why Should You Care?].

• Question 46:

  You are troubleshooting a problem with a new 802.11ax AP. While the AP supports four spatial streams, most clients are only achieving maximum data rates of 150 Mbps. What is the likely cause?

  A. The clients are 802.11n devices
  B. The clients are only two stream 802.11ax clients
  C. Contention caused by an overlapping BSS
  D. Non-Wi-Fi interference in the channel
  A. The clients are 802.11n devices

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  Explanation/Reference:

  The scenario described suggests that while the Access Point (AP) is capable of 802.11ax (Wi-Fi 6) with four spatial streams, the clients are only achieving data rates typical of 802.11n (Wi-Fi 4) devices, which indicates that the clients are

  likely 802.11n devices. Here's why this is the most plausible explanation:

  802.11n Limitations: Devices that adhere to the 802.11n standard have lower maximum data rates compared to 802.11ax devices due to differences in technology such as modulation, spatial streams, and channel bandwidth. An 802.11n

  device with a single spatial stream operating on a 20 MHz channel can achieve a maximum data rate of 72.2 Mbps. Even with two spatial streams under ideal conditions, this would only double to approximately 144.4 Mbps, which is close to

  the 150 Mbps mentioned.

  Spatial Stream Capability: The fact that the AP supports four spatial streams suggests it can achieve much higher data rates with 802.11ax clients that also support multiple spatial streams. However, if the clients are 802.11n devices, they

  may not be capable of using more than two spatial streams, and many earlier 802.11n devices were limited to just one.

  The other options are less likely to be the primary cause based on the information provided:

  B. Two Stream 802.11ax Clients: If the clients were 802.11ax with only two spatial streams, they would likely achieve higher data rates than 150 Mbps due to the efficiency improvements in 802.11ax.

  C. Contention and D. Non-Wi-Fi Interference: While these could affect performance, they would not inherently limit clients to 150 Mbps,especially in the context of an 802.11ax environment where mechanisms to handle interference and

  contention are more advanced.

  References:

  IEEE 802.11n-2009: Enhancements for Higher Throughput. CWNA Certified Wireless Network Administrator Official Study Guide: Exam PW0- 105, by David D. Coleman and David A. Westcott.

• Question 47:

  When compared with legacy Power Save mode, how does VHT TXOP power save improve battery life for devices on a WLAN?

  A. Legacy Power Save mode was removed in the 802.11ac amendment.
  B. VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.
  C. VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.
  D. VHT TXOP power save allows stations to enter sleep mode and legacy Power Save does not.
  B. VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.

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  Explanation/Reference:

  VHT TXOP (Very High Throughput Transmit Opportunity) power save is a feature introduced with the 802.11ac amendment, which is designed to improve the power efficiency of devices connected to a WLAN. This feature enhances battery

  life in several ways, compared to the legacy Power Save mode:

  Enhanced Power Saving: VHT TXOP power save allows devices to disable more components of the WLAN transceiver when they are in a low power state. This reduces the power consumption during periods when the device is not actively

  transmitting or receiving data.

  Intelligent Wake-Up Mechanisms: It employs more sophisticated mechanisms for devices to determine when they need to wake up and listen to the channel, further reducing unnecessary power usage.

  Optimized Operation: This power save mode is optimized for the high-throughput environment of 802.11ac networks, allowing devices to efficiently manage power while maintaining high performance.

  Legacy Power Save mode, introduced in earlier versions of the 802.11 standards, does not provide the same level of component disablement or the intelligent wake-up mechanisms found in VHT TXOP power save, making option B the

  correct answer.

  References:

  IEEE 802.11ac-2013 Amendment: Enhancements for Very High Throughput for Operation in Bands below 6 GHz.

  CWNA Certified Wireless Network Administrator Official Study Guide:

  ExamCWNA-109, by David D. Coleman and David A. Westcott.

• Question 48:

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

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  Explanation/Reference:

  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

• Question 49:

  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 frame was not delivered and must be retransmitted
  D. The receiver is offline
  C. The frame was not delivered and must be retransmitted

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  Explanation/Reference:

  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.

• Question 50:

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

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

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  Explanation/Reference:

  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.