CWNP CWNA-109 Online Practice Questions and Exam Preparation

CWNP CWNA-109 Online Questions & Answers

• Question 1:

  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 client drivers are faulty and should be upgraded.
  C. The antennas in the laptop have insufficient gain to detect the 5 GHz signals.
  D. The access points are configured to disallow 5 GHz.
  B. The client drivers are faulty and should be upgraded.

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  Explanation/Reference:

  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 If the client drivers are faulty, outdated, or incompatible, they may cause various issues with the wireless performance and functionality, such as low data rates, poor signal strength, frequent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

• Question 2:

  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
  C. Counter Mode with CBC-MAC Pro tocol

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  Explanation/Reference:

  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 3:

  What statement about the IEEE 802.11-2016 QoS facility is true?

  A. 802.11 control frames are assigned to the 802.11 EF priority queue.
  B. When the Voice queue has frames awaiting transmission, no data will be transmitted from the Best Effort queue.
  C. 802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention.
  D. Four 802.1p user priorities are mapped to eight 802.11 transmit queues.
  C. 802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention.

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  Explanation/Reference:

  802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention. 802.11 QoS is based on the Enhanced Distributed Channel Access (EDCA) mechanism, which defines four access categories (ACs) for different types of traffic: Voice, Video, Best Effort, and Background. Each AC has its own transmit queue and contention parameters, such as Arbitration Interframe Space (AIFS), Contention Window (CW), and Transmission Opportunity (TXOP). These parameters determine how long a station has to wait before transmitting a frame and how long it can occupy the channel. Higher priority ACs have shorter AIFS, smaller CW, and longer TXOP, which means they have more chances to access the channel and send more data than lower priority ACs. However, this does not guarantee that higher priority ACs will always win the contention, as there is still a random backoff process involved. Therefore, 802.11 QoS is a statistical service that provides different levels of service quality based on traffic categories. References: , Chapter 10, page 403; , Section 6.1

• Question 4:

  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
  B. BSS Color

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  Explanation/Reference:

  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 5:

  You must plan for POE in an office environment. Which one of these devices is least likely to be a POE PSE?

  A. Midspan multi-port injector
  B. Switch
  C. VolP Phone
  D. Midspan injector
  C. VolP Phone

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  Explanation/Reference:

  A VoIP phone is least likely to be a POE PSE of the devices listed. POE stands for Power over Ethernet, which is a technology that allows devices to receive both power and data over a single Ethernet cable. A POE PSE stands for Power Sourcing Equipment, which is a device that provides power to other devices over Ethernet. A POE PD stands for Powered Device, which is a device that receives power from a PSE over Ethernet. A midspan multi- port injector, a switch, and a midspan injector are examples of POE PSEs, as they can supply power to multiple devices over Ethernet cables. A VoIP phone is an example of a POE PD, as it can receive power from a PSE over an Ethernet cable. However, some VoIP phones can also act as POE PSEs for other devices, such as IP cameras or wireless access points, but this is not very common. References: CWNA-109 Study Guide, Chapter

  8: Wireless LAN Access Points, page 2411

• Question 6:

  What statement about the beamwidth of an RF antenna is true?

  A. Horizontal and vertical beamwidth are calculated at the points where the main lobe decreases power by 3 dB.
  B. The beamwidth patterns on an antenna polar chart indicate the point at which the RF signal stops propagating.
  C. When antenna gain is lower, the beamwidth is also lower in both the horizontal and vertical dimensions.
  D. Vertical beamwidth is displayed (in degrees) on the antenna's Azimuth chart.
  A. Horizontal and vertical beamwidth are calculated at the points where the main lobe decreases power by 3 dB.

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  Explanation/Reference:

  The beamwidth of an RF antenna is the angular measure of how wide the main lobe of radiation is. The main lobe is the area where the signal strength is highest and most concentrated. The beamwidth is calculated at the points where the main lobe decreases power by 3 dB, which means it is half of the maximum power. The beamwidth can be measured in both horizontal and vertical planes, depending on how the antenna is oriented. The horizontal beamwidth is also called azimuth, while the vertical beamwidth is also called elevation. The beamwidth patterns on an antenna polar chart indicate how the RF energy is distributed in different directions. References: 1, Chapter 2, page 66; 2, Section 2.3

• Question 7:

  What statement about 802.11 WLAN bridges is true?

  A. WLAN bridges only work in the 2.4 GHz frequency band and they support only SISO communications
  B. WLAN bridges must use a channel with acceptable SNR at both transceivers to maintain the desired data rate bi-directionally
  C. WLAN bridges may support MIMO communications, but only if used in the 5 GHz frequency band
  D. WLAN bridges must be implemented such that no interference occurs on the channel anywhere between the two endpoints used to establish the bridge
  B. WLAN bridges must use a channel with acceptable SNR at both transceivers to maintain the desired data rate bi-directionally

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  Explanation/Reference:

  WLAN bridges must use a channel with acceptable SNR at both transceivers to maintain the desired data rate bi-directionally. A WLAN bridge is a device that connects two or more networks using the 802.11 protocol. A WLAN bridge must have a clear and strong signal between the two endpoints to ensure reliable and fast data transmission. The signal-to- noise ratio (SNR) is a measure of the quality of the signal, which depends on the distance, interference, obstacles, and antenna gain between the transceivers. A higher SNR means a better signal quality and a higher data rate. A lower SNR means a worse signal quality and a lower data rate. Therefore, a WLAN bridge must use a channel with acceptable SNR at both transceivers to maintain the desired data rate bi-directionally1.

• Question 8:

  What statement describes the authorization component of a AAA implementation?

  A. Verifying that a user is who he says he is.
  B. Implementing a WIPS as a full-time monitoring solution to enforce policies.
  C. Granting access to specific network services or resources according to a user profile.
  D. Validating client device credentials against a database.
  C. Granting access to specific network services or resources according to a user profile.

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  Explanation/Reference:

  Granting access to specific network services or resources according to a user profile describes the authorization component of a AAA implementation. AAA stands for Authentication, Authorization, and Accounting, which are three functions that are used to control and monitor access to network resources and services. Authentication is the process of verifying that a user is who he says he is, by using credentials such as username, password, certificate, token, or biometric data. Authorization is the process of granting access to specific network services or resources according to a user profile, which defines the user's role, privileges, and permissions. Accounting is the process of recording and reporting the usage of network services or resources by a user, such as the duration, volume, type, and location of the access. AAA can be implemented by using different protocols andservers, such as RADIUS, TACACS+, LDAP, Kerberos, or Active Directory. References: 1, Chapter 11, page 449; 2, Section 7.1

• Question 9:

  You have implemented an 802.11ax WLAN for a customer. All APs are four stream HE APs. The customer states that it is essential that most of the clients can use the OFDMA modulation scheme. What do you tell the customer?

  A. The clients that must support OFDMA must also be upgraded to 802.11ax
  B. OFDMA is an optional feature of 802.11ax and most APs don't even support it
  C. All 5 GHz PHYs use OFDM modulation, so you will achieve OFDMA everywhere in 5 GHz
  D. If the devices support 802.11ac, they can be updated to support OFDMA through driver upgrades
  A. The clients that must support OFDMA must also be upgraded to 802.11ax

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  Explanation/Reference:

  OFDMA is a new modulation scheme introduced in 802.11ax that allows multiple users to share the same channel by dividing it into smaller subchannels called resource units (RUs). This improves the efficiency and capacity of the WLAN by reducing contention and overhead. However, to use OFDMA, both the AP and the client must support 802.11ax and negotiate the parameters of the subchannel allocation. Therefore, the customer needs to upgrade the clients that require OFDMA to 802.11ax devices12. The other options are not correct because they do not reflect the reality of OFDMA. Option B is incorrect because OFDMA is a mandatory feature of 802.11ax for both downlink and uplink transmissions, and all 802.11ax APs must support it1. Option C is incorrect because OFDM and OFDMA are different modulation schemes, and OFDM does not allow multiple users to share the same channel. Option D is incorrect because 802.11ac devices cannot support OFDMA through driver upgrades, as they lack the hardware and firmware capabilities to do so2. References: 1:CWNA-109Official Study Guide, page 144 2: OFDMA

• Question 10:

  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
  C. Overlay WLAN monitoring solution

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  Explanation/Reference:

  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.