CWNP CWNP Certifications CWNA-109 Questions & Answers

• Question 81:

  What statement about 802.3, Clause 33 Power over Ethernet is true?

  A. When using CAT5 cabling, you increase the maximum draw available to the PD over that available with CAT6.

  B. Only endpoint PSEs are supported.

  C. Only midspan PSEs are supported.

  D. The lowest voltage drop is achieved when using CAT6 cable instead of Cat5 or CAT5e.

  Correct Answer: D

  https://www.cablinginstall.com/articles/2012/08/cat-6a-vs-cat-5e-poe.html The statement that the lowest voltage drop is achieved when using CAT6 cable instead of Cat5 or CAT5e is true about 802.3, Clause 33 Power over Ethernet. Power over Ethernet (PoE) is a technology that allows electrical power to be delivered over Ethernet cables along with data signals. PoE is defined by IEEE 802.3, Clause 33 and has several variants, such as PoE (802.3af), PoE+ (802.3at), and PoE ++ (802.3bt). PoE works by using a device called PSE (Power Sourcing Equipment) that injects power into the Ethernet cable and a device called PD (Powered Device) that receives power from the Ethernet cable. The PSE can be either an endpoint device, such as a switch or a router, or a midspan device, such as an injector or a splitter, that is inserted between two Ethernet devices. The PD can be any device that requires power, such as an access point, a camera, or a phone. One of the factors that affects PoE performance is voltage drop, which is the reduction of voltage that occurs as current flows through a cable due to its resistance. Voltage drop can cause power loss and inefficiency in PoE systems, as well as damage to PDs if the voltage falls below their minimum requirement. To minimize voltage drop, it is recommended to use high-quality cables with low resistance and short length. Among the common types of Ethernet cables, CAT6 has the lowest resistance and therefore the lowest voltage drop compared to Cat5 or CAT5e. CAT6 also has higher bandwidth and data rate than Cat5 or CAT5e, making it more suitable for PoE applications. References: 1, Chapter 7, page 263; 2, Section 4.4

• Question 82:

  You are evaluating a connection that states the data rate is 150 Mbps. What is the expected throughput of this connection?

  A. Less than 150 Mbps because of 802.11 overhead and contention

  B. 54 Mbps because that is the actual maximum throughput of an 802.11 connection

  C. More than 150 Mbps because of compression

  D. 150 Mbps because the data rate is equal to the throughput

  Correct Answer: A

  The data rate of a signal is the speed that the data bits in individual 802.11 data frames are sent, but it does not account for the actual amount of data that can be transmitted over time. The throughput of a connection is the flow of information over time, which is affected by various factors such as data encoding, modulation, encryption, airtime utilization, noise levels, interference, etc. Therefore, the throughput is always lower than the data rate. According to one of the web search results1, the actual throughput is normally 60-70 percent of the supported data rates. So, for a connection with a data rate of 150 Mbps, the expected throughput would be around 90-105 Mbps.

• Question 83:

  In which plane of the three networking planes is an access point configured by a WLAN controller?

  A. Control

  B. Management

  C. Security

  D. Data

  Correct Answer: B

  An access point is configured by a WLAN controller in the management plane of the three networking planes. The management plane is responsible for the configuration, administration, and monitoring of network devices, such as access points, switches, routers, and controllers. The WLAN controller communicates with the access point using a management protocol, such as CAPWAP or SNMP, to send configuration commands and receive status information. The control plane is responsible for the routing, switching, and forwarding of network traffic, such as data frames and control frames. The WLAN controller may also participate in the control plane by performing functions such as authentication, encryption, roaming, and load balancing. The security plane is responsible for the protection of network devices and data from unauthorized access, modification, or disclosure. The WLAN controller may also participate in the security plane by implementing features such as firewall, VPN, IDS/IPS, and WIPS. The data plane is responsible for the transmission and reception of user data, such as voice, video, or web traffic. The WLAN controller may or may not participate in the data plane depending on the architecture of the WLAN. In some cases, the access point forwards the user data directly to the wired network without involving the WLAN controller (distributed data forwarding). In other cases, the access point tunnels the user data to the WLAN controller before forwarding it to the wired network (centralized data forwarding). References: CWNA-109 Study Guide, Chapter

  9: Wireless LAN Architecture, page 279

• Question 84:

  What terms accurately complete the following sentence?

  The IEEE 802.11-2016 standard specifies mandatory support of the _______________ cipher suite for Robust Security Network Associations, and optional use of the ________________ cipher suite, which is designed for use with pre-RSNA hardware and is deprecated.

  A. 802.1X/EAP, WEP

  B. CCMP, TKIP

  C. TLS, SSL

  D. RC5, RC4

  Correct Answer: B

• Question 85:

  What is appended to the end of each 802.11 data frame after the payload?

  A. Preamble

  B. MAC header

  C. PHY header

  D. FCS

  Correct Answer: D

  The FCS (Frame Check Sequence) is appended to the end of each 802.11 data frame after the payload. The FCS is a 4-byte field that contains a CRC-32 (Cyclic Redundancy Check) value that is calculated based on the contents of the MAC header and the payload of the frame. The FCS is used by the receiver to verify the integrity of the frame and to detect any errors or corruption that may have occurred during transmission. If the FCS does not match with the expected value, the frame is discarded by the receiver. References: , Chapter 4, page 139; , Section 4.2

• Question 86:

  When antenna gain is reported in dBi, the gain of the antenna is compared to what theoretical radiator?

  A. End-fire radiator

  B. Dipole radiator

  C. Isotropic radiator D. Anthropomorphic radiator

  Correct Answer: C

  An isotropic radiator is a theoretical point source of electromagnetic radiation that radiates equally in all directions. It has no physical dimensions and no preferred direction of radiation. It is used as a reference for antenna gain because it represents the ideal case of a perfect omnidirectional antenna12 Antenna gain is a measure of how well an antenna concentrates its radiated power in a certain direction. It is expressed in decibels (dB) relative to a reference antenna. Whenthe reference antenna is an isotropic radiator, the antenna gain is denoted by dBi, which stands for decibels relative to isotropic12 For example, an antenna with a gain of 3 dBi means that it radiates 3 dB more power in its main direction than an isotropic radiator would. Conversely, an antenna with a gain of -3 dBi means that it radiates 3 dB less power in its main direction than an isotropic radiator would12

• Question 87:

  You are troubleshooting a client problem with a 2.4 GHz WLAN connection. The client is experiencing surprisingly low data rates during the work day. You analyze the workspace outside of business hours and detect a strong signal with a typical noise floor at the client location. During working hours, the user works with a laptop in the area and uses an external USB hard drive for continuous data access. The user also states that the laptop works as expected on her home network. The user working approximately 8 feet away from this client experiences no problems.

  Based on this information, what is the likely cause of the problem?

  A. The AP is overloaded during the work day

  B. The drivers in the laptop are corrupt

  C. The laptop has a failing wireless adapter

  D. The external hard drive is USB 3.0 and is causing a significant increase in the noise floor when in use

  Correct Answer: D

  The likely cause of the problem is that the external hard drive is USB 3.0 and is causing a significant increase in the noise floor when in use. USB 3.0 devices are known to generate radio frequency interference (RFI) in the 2.4 GHz band due to their high data transfer rates and harmonics. This RFI can increase the noise floor and degrade the signal- to-noise ratio (SNR) of WLAN devices operating in the same band. This can result in lower data rates, reduced throughput, increased retransmissions, and poor performance. The problem may not occur outside of business hours or on the user's home network because of different usage patterns or environmental factors. References: [CWNP Certified Wireless Network Administrator Official StudyGuide: ExamCWNA-109], page 527; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 497.

• Question 88:

  What security solution is required to be used in place of Open System Authentication for all open network 802.11 implementations in the 6 GHz band?

  A. OWE

  B. Kerberos

  C. WPA3-Enterprise

  D. WPA3-SAE

  Correct Answer: A

• Question 89:

  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. Access point spectrum analyzer

  B. Laptop-based spectrum analyzer with an omni-directional antenna

  C. Laptop-based spectrum analyzer with an omni-directional antenna

  D. Laptop-based spectrum analyzer with a directional antenna

  Correct Answer: D

  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

• Question 90:

  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.

  Correct Answer: A

  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