CWNP CWNP Certifications CWNA-109 Questions & Answers

• Question 31:

  What cipher suite is specified by the 802.11-2016 standard and is not deprecated?

  A. Wired Equivalent Privacy

  B. Temporal Key Integrity Protocol

  C. Counter Mode with CBC-MAC Pro tocol

  D. Extensible Authentication Protocol

  Correct Answer: C

  The cipher suite specified by the 802.11-2016 standard and is not deprecated is Counter Mode with CBC-MAC Protocol (CCMP). CCMP is an encryption protocol that uses Advanced Encryption Standard (AES) as the underlying cipher and

  provides confidentiality, integrity, and origin authentication for wireless data. CCMP is the mandatory encryption protocol for WPA2 and WPA3. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA109], page 295; [IEEE Standard for Information technology璗elecommunications and information exchange between systems Local and metropolitan area networks璖pecific requirements - Part 11:

  Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications], page 1560.

• Question 32:

  You manage a WLAN with 100 802.11ac access points. All access points are configured to use 80 MHz channels. In a particular BSS, only 40 MHz communications are seen. What is the likely cause of this behavior?

  A. All clients implement single spatial stream radios

  B. The clients are all 802.11n STAs or lower

  C. The AP is improperly configured to use only 40 MHz of the 80 MHz allocated bandwidth

  D. The short guard interval is also enabled

  Correct Answer: B

  https://7signal.com/802-11ac-migration-part-2-whats-nobodys-telling-you- about-80mhz-and-160mhz-channel-bonding The clients are all 802.11n STAs or lower is the likely cause of this behavior. If a WLAN with 100 802.11ac access points is configured to use 80 MHz channels, butonly 40 MHz communications are seen in a particular BSS, it means that the clients in that BSS do not support 80 MHz channels. This could be because they are using older standards, such as 802.11n or lower, that do not support 80 MHz channels. Alternatively, they could be using newer standards, such as 802.11ac or ax, but have their channel width settings limited to 40 MHz or lower due to device capabilities or configuration options. In either case, the AP will adapt to the client's channel width and use only 40 MHz of the 80 MHz allocated bandwidth to communicate with them. This will reduce the potential throughput and efficiency of the WLAN. References: , Chapter 3, page 111; , Section 3.2

• Question 33:

  In addition to coverage analysis results, what should be included in a post-deployment site survey report to ensure WLAN users experience acceptable performance?

  A. WAN interface analysis results

  B. Capacity analysis results

  C. Application Layer protocol availability analysis results

  D. Layer 4 protocol availability analysis results

  Correct Answer: B

  In addition to coverage analysis results, what should be included in a post- deployment site survey report to ensure WLAN users experience acceptable performance is Capacity analysis results. Capacity analysis is a method of testing the ability of the WLAN to support the expected number and type of users, devices, and applications. Capacity analysis can help to determine the optimal number and placement of access points, the appropriate channel and power settings, the required QoS policies, and the expected throughput and latency levels. Capacity analysis results can help to verify that the WLAN meets the performance requirements and service level agreements (SLAs) of the organization. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 548; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 518.

• Question 34:

  A dual-band 802.11ac AP must be powered by PoE. As a class 4 device, what power level should be received at the AP?

  A. 30 W

  B. 12.95 W

  C. 25.5 W D. 15.4 W

  Correct Answer: C

  PoE has different standards that define different power levels for PSEs and PDs. The original standard, IEEE 802.3af, defines two classes of PSEs: Class 3 (15.4 W) and Class 4 (30 W). The newer standard, IEEE 802.3at, also known as PoE +, defines four classes of PSEs: Class 0 (15.4 W), Class 1 (4 W), Class 2 (7 W), and Class 3 (12.95 W). The power level received at the PD is always lower than the power level provided by the PSE, due to cable resistance and power dissipation. The IEEE standards specify the minimum power level that must be received at the PD for each class of PSE. For a Class 4 PSE, the minimum power level received at the PD is 25.5 W910. References: CWNA-109 Study Guide, Chapter 7: Power over Ethernet (PoE), page 295; CWNA-109Study Guide, Chapter

  7: Power over Ethernet (PoE), page 289.

• Question 35:

  What feature of 802.1 lax (HE) may impact design decisions related to AP placement and the spacing between same-channel BSS cells (3SAs) because it is designed to reduce overlapping BSS contention?

  A. TWT

  B. BSS Color

  C. uplink MU-MIMO

  D. 6 GHz band support

  Correct Answer: B

  In the 802.11ax (High Efficiency, HE) amendment, one of the key features introduced is BSS (Basic Service Set) Coloring. This feature is designed to mitigate issues arising from overlapping BSSs (OBSS), which can lead to contention and

  interference in dense wireless environments. BSS Coloring works by:

  Assigning a "color" (a small number) to each BSS: This helps devices differentiate between frames from their own BSS and those from neighboring BSSs. Reducing Inter-BSS Interference: Devices can ignore frames from different BSSs (with

  a different "color") under certain conditions, reducing the impact of OBSS interference.

  Improving Spatial Reuse: By distinguishing between transmissions from different BSSs, devices can make more informed decisions about when to transmit, improving the efficiency of spatial reuse and reducing unnecessary contention. This

  feature directly impacts design decisions related to AP placement and the spacing between same-channel BSS cells, as it allows for closer placement of APs on the same channel without significantly increasing interference, thus improving

  overall network capacity and efficiency.

  The other options, while features of 802.11ax, do not directly pertain to reducing overlapping BSS contention in the same manner:

  TWT (Target Wake Time)optimizes device sleep schedules to conserve power. Uplink MU-MIMOenhances uplink data transmission capabilities but doesn't specifically address OBSS contention.

  6 GHz Band Supportintroduces new spectrum for Wi-Fi use but is not a feature aimed at reducing OBSS contention within the 802.11ax framework.

  Therefore, the correct answer is B, BSS Color.

  References:

  IEEE 802.11ax-2021: Enhancements for High Efficiency WLAN. CWNA Certified Wireless Network Administrator Official Study Guide:

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

• Question 36:

  When considering data rates available in HT and VHT PHY devices, in addition to the modulation, coding, channel width, and spatial streams, what impacts the data rate according to the MCS tables?

  A. Frequency band in use

  B. client drivers

  C. guard interval

  D. Antenna Height

  Correct Answer: C

  The guard interval is a short period of time inserted between the symbols of an OFDM signal to prevent inter-symbol interference and improve the robustness of the transmission1. The guard interval can have different values depending on

  the 802.11 standard and the configuration of the device. For example, 802.11n supports two guard intervals: 800 ns (normal) and 400 ns (short)2. 802.11ac supports the same guard intervals as 802.11n, plus an optional 200 ns guard interval

  for 80 MHz and 160 MHz channels3. 802.11ax supports three guard intervals: 800 ns, 1600 ns, and 3200 ns4. The guard interval affects the data rate because it determines the duration of each symbol. A shorter guard interval means more

  symbols can be transmitted in a given time, resulting in a higher data rate. However, a shorter guard interval also means less protection against inter-symbol interference, which may degrade the signal quality and increase the error rate.

  Therefore, there is a trade-off between data rate and reliability when choosing the guard interval.

  The MCS tables for HT and VHT PHY devices show the data rates for different combinations of modulation, coding, channel width, spatial streams, and guard intervals. For example, for a VHT device using MCS 9 with QAM-256 modulation,

  5/6 coding rate, 80 MHz channel width, and one spatial stream, the data rate is 433.3 Mbps with a normal guard interval (800 ns) and 486.7 Mbps with a short guard interval (400 ns)2. Therefore, the guard interval impacts the data rate

  according to the MCS tables.

• Question 37:

  You are troubleshooting a controller-based AP that is unable to locate the controller. DHCP is not use and the controller is located at 10.10.10.81/24 while the AP is on the 10.10.16.0/24 network. What should be inspected to verify proper configuration?

  A. NTP

  B. BOOTH

  C. DNS

  D. AP hosts file

  Correct Answer: C

  What should be inspected to verify proper configuration is DNS. DNS stands for Domain Name System and is a service that resolves hostnames to IP addresses. In a controller- based AP deployment, DNS can be used to help the AP locate the controller by using a predefined hostname such as CISCO-CAPWAP-CONTROLLER or aruba-master. The AP sends a DNS query for this hostname and receives an IP address of the controller as a response. Therefore, if DNS is not configured properly or if there is no DNS entry for the controller hostname, the AP may not be able to locate the controller. NTP, BOOTP, and AP hosts file are not relevant for this scenario. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 374; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 364.

• Question 38:

  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. Laptop-based spectrum analyzers

  B. AP-based spectrum analysis

  C. Overlay WLAN monitoring solution

  D. Laptop-based protocol analyzers

  Correct Answer: C

  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.

• Question 39:

  What common feature of MDM solutions can be used to protect enterprise data on mobile devices?

  A. Over-the-air registration

  B. Onboarding

  C. Containerization

  D. Self-registration

  Correct Answer: C

  A common feature of MDM solutions that can be used to protect enterprise data on mobile devices is containerization. Containerization is a technique that creates a separate and secure environment on the mobile device where enterprise data and applications are stored and accessed. Containerization isolates the enterprise data from the personal data and prevents unauthorized access, leakage, or loss of sensitive information. Containerization can also enforce security policies, encryption, authentication, and remote wipe on the enterprise data and applications. Over-the-air registration, onboarding, and self-registration are features of MDM solutions that facilitate the enrollment and management of mobile devices, but they do not directly protect enterprise data on mobile devices. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 336; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 326.

• Question 40:

  You are using a tool that allows you to see signal strength for all Aps in the area with a visual representation. It shows you SSIDs available and the security settings for each SSID. It allows you to filter by frequency band to see only 2.4 GHz networks or only 5 GHz networks. No additional features are available.

  What kind of application is described?

  A. Protocol analyzer

  B. Site survey utility

  C. Spectrum analyzer

  D. WLAN scanner tool

  Correct Answer: D

  The tool described is a WLAN (Wireless Local Area Network) scanner tool. WLAN scanner tools are designed to provide information about the wireless networks in a given area, including: Signal Strength: They show the signal strength of all access points (APs) in the vicinity, which is crucial for understanding the coverage area and potential interference.

  SSID Visualization: These tools display the SSIDs (Service Set Identifiers) of available networks, allowing users to identify different wireless networks easily. Security Settings Information: WLAN scanner tools often show the type of security

  implemented on each network, such as WPA2, WEP, etc. Frequency Band Filtering: They allow users to filter and view networks based on the frequency band (2.4 GHz or 5 GHz), which is useful for analyzing network distribution and

  planning.

  While protocol analyzers, site survey utilities, and spectrum analyzers are also used in wireless networking, their functions are distinct from what is described:

  Protocol Analyzersare more sophisticated and are used to capture and analyze network traffic.

  Site Survey Utilitiesare used to map signal coverage and plan network layouts, often with more advanced features for detailed site surveys. Spectrum Analyzersprovide a detailed view of the frequency spectrum and non- Wi-Fi interference

  but don't typically focus on SSIDs or security settings. Thus, the correct answer is D, a WLAN scanner tool, based on the functionalities described.

  References:

  CWNA Certified Wireless Network Administrator Official Study Guide: Exam PW0- 105, by David D. Coleman and David A. Westcott.

  Tools and techniques for wireless network analysis and troubleshooting.