Give Push to your Success with CWNA Certification CWNA-109 Exam Questions
CWNA-109 100% Guarantee Download CWNA-109 Exam PDF Q&A
NEW QUESTION # 67
You are installing an AP to be used by 27 laptops. All laptops will connect on the 5 GHz frequency band. A neighbor network uses channels 1 and 6. What channel should be used for this AP and why?
- A. Channel 11, because channels 1 and 6 are in use nearby
- B. A 5 GHz channel, because channels 1 and 6 are 2.4 GHz channels they have no impact on the decision
- C. Channel 6, because it is always best to use this channel
- D. Channel 1, because it is best to use the channel with the lowest frequency
Answer: B
Explanation:
A 5 GHz channel should be used for this AP because channels 1 and 6 are 2.4 GHz channels and they have no impact on the decision. The 5 GHz frequency band offers more non-overlapping channels than the 2.4 GHz frequency band, which reduces interference and improves performance. The 5 GHz frequency band also supports higher data rates and wider channel bandwidths than the 2.4 GHz frequency band, which increases capacity and throughput. The 5 GHz frequency band also has less interference from other devices and sources than the 2.4 GHz frequency band, which enhances reliability and quality of service. Therefore, it is recommended to use the 5 GHz frequency band for WLANs whenever possible. Channels 1 and 6 are two of the three non-overlapping channels in the 2.4 GHz frequency band (the other one is channel 11). They are used by a neighbor network in this scenario, but they do not affect the channel selection for this AP because they operate in a different frequency band than the 5 GHz frequency band. Channel 6 is not always best to use; it depends on the interference and congestion level in the environment. Channel 1 is not best to use because it has a lower frequency than channel 6; frequency does not determine channel quality or performance. Channel
11 is not best to use because it is also a 2.4 GHz channel and it may interfere with channels 1 and
6. References: CWNA-109 Study Guide, Chapter 4: Antenna Systems and Radio Frequency (RF) Components, page 113
NEW QUESTION # 68
You are reporting on the RF environment in your facility. The manager asks you to describe the noise floor noted in the report. Which of the following is the best explanation?
- A. The energy radiated by flooring materials that causes interference in the 2.4 GHz and 5 GHz bands.
- B. The RF energy that exists in the environment from intentional and unintentional RF radiators that forms the baseline above which the intentional signal of your WLAN must exist.
- C. The extra energy radiated by access points and client devices beyond that intended for the signal.
- D. The noise caused by elevators, microwave ovens, and video transmitters.
Answer: B
Explanation:
The RF energy that exists in the environment from intentional and unintentional RF radiators that forms the baseline above which the intentional signal of your WLAN must exist is the best explanation of the noise floor noted in the report. The noise floor is a term that describes the level of background noise or interference in a wireless channel or band. The noise floor is measured in dBm (decibel-milliwatts) and it represents the minimum signal strength that can be detected or received by a wireless device. The noise floor is influenced by various factors, such as the sensitivity of the receiver, the antenna gain, the cable loss, and the ambient RF environment. The ambient RF environment consists of intentional and unintentional RF radiators that emit RF energy in the wireless spectrum. Intentional RF radiators are devices that are designed to transmit RF signals for communication purposes, such as Wi-Fi access points, Bluetooth devices, microwave ovens, or cordless phones. Unintentional RF radiators are devices that are not designed to transmit RF signals but generate electromagnetic radiation as a by-product of their operation, such as USB 3 devices, PC power supplies, or fluorescent lights. The noise floor affects WLAN performance and quality because it determines the minimum signal-to-noise ratio (SNR) that is required for a successful wireless transmission. SNR is the difference between the signal strength of the desired signal and the noise floor of the channel. SNR is also measured in dB and it indicates how much the signal stands out from the noise. A higher SNR means a better signal quality and a lower bit error rate. A lower SNR means a worse signal quality and a higher bit error rate. Therefore, to achieve a reliable WLAN connection, the intentional signal of your WLAN must exist above the noise floor by a certain margin that depends on the data rate and modulation scheme used. The other options are not accurate or complete explanations of the noise floor noted in the report. The noise caused by elevators, microwave ovens, and video transmitters is not the noise floor but rather examples of interference sources that contribute to the noise floor. The extra energy radiated by access points and client devices beyond that intended for the signal is not the noise floor but rather an example of spurious emissions that cause interference to other devices or channels. The energy radiated by flooring materials that causes interference in the 2.4 GHz and 5 GHz bands is not the noise floor but rather an example of attenuation or reflection that reduces or changes the direction of the signal. References: CWNA-109 Study Guide, Chapter 5: Radio Frequency Signal and Antenna Concepts, page 139
NEW QUESTION # 69
When using a spectrum to look for non Wi-Fi interference sources, you notice significant interference across the entire 2.4 GHz band (not on a few select frequencies) within the desktop area of a users workspace, but the interference disappears quickly after just 2 meters. What is the most likely cause of this interference?
- A. Unintentional radiation from the PC power supply
- B. USB 3 devices in the user's work area
- C. Excess RF energy from a nearby AP
- D. Bluetooth devices in the user's work area
Answer: B
Explanation:
USB 3 devices in the user's work area are the most likely cause of this interference when using a spectrum analyzer to look for non-Wi-Fi interference sources. A spectrum analyzer is a tool that measures and visualizes the radio frequency activity and interference in the wireless environment. A spectrum analyzer can show the spectrum usage and energy levels on each frequency band or channel and help identify and locate the sources of interference. Interference is any unwanted signal that disrupts or degrades the intended signal on a wireless channel. Interference can be caused by various sources, such as other Wi-Fi devices, non-Wi-Fi devices, or natural phenomena. Interference can affect WLAN performance and quality by causing signal loss, noise, distortion, or errors. USB 3 devices are non-Wi-Fi devices that use USB 3.0 technology to transfer data at high speeds between computers and peripherals, such as hard drives, flash drives, cameras, or printers.
USB 3 devices can generate electromagnetic radiation that interferes with Wi-Fi signals in the 2.4 GHz band, especially when they are close to Wi-Fi devices or antennas. USB 3 devices can cause significant interference across the entire 2.4 GHz band (not on a few select frequencies) within the desktop area of a user's workspace, but the interference disappears quickly after just 2 meters. This is because USB 3 devices emit broadband interference that affects all channels in the 2.4 GHz band with a high intensity near the source but a low intensity at a distance due to attenuation. The other options are not likely to cause this interference pattern when using a spectrum analyzer to look for non-Wi-Fi interference sources. Bluetooth devices in the user's work area are non-Wi-Fi devices that use Bluetooth technology to communicate wirelessly between computers and peripherals, such as keyboards, mice, headphones, or speakers. Bluetooth devices can cause interference with Wi-Fi signals in the 2.4 GHz band, but they use frequency hopping spread spectrum (FHSS) technique that changes frequencies rapidly and randomly within a range of 79 channels. Therefore, Bluetooth devices do not cause significant interference across the entire 2.4 GHz band (not on a few select frequencies), but rather intermittent interference on some channels at different times. Excess RF energy from a nearby AP is not a non-Wi-Fi interference source but rather a Wi-Fi interference source that occurs when an AP transmits more power than necessary for its coverage area. Excess RF energy from a nearby AP can cause co- channel interference (CCI) with other APs or client devices that use the same channel within range of each other. CCI reduces performance and capacity because it causes contention and collisions on the wireless medium,
NEW QUESTION # 70
A WLAN transmitter that emits a 50 mW signal is connected to a cable with 3 dB loss. If the cable is connected to an antenna with 9dBi gain, what is the EIRP at the antenna element?
- A. 26 dBm
- B. 13 dBm
- C. 23 dBm
- D. 10 dBm
Answer: C
Explanation:
To calculate the EIRP at the antenna element, we need to add the transmitter output power, subtract the cable loss, and add the antenna gain. All these values need to be converted to dBm first, if they are not already given in that unit. In this case, we have:
Transmitter output power = 50 mW = 10 log (50) dBm = 16.99 dBm Cable loss = 3 dB Antenna gain = 9 dBi EIRP = Transmitter output power - Cable loss + Antenna gain EIRP = 16.99 - 3 + 9 EIRP = 22.99 dBm Rounding up to the nearest integer, we get 23 dBm as the EIRP at the antenna element12. References: CWNA-
109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 92; CWNA-109 Study Guide, Chapter 2:
Radio Frequency Fundamentals, page 88.
NEW QUESTION # 71
You are deploying a WLAN with the access points configured for 10 mW of output power on the 2.4 GHz radios and 20 mW of output power on the 5GHz radios. Some semi-directional antennas are also in use. What kind of deployment is described?
- A. SOHO
- B. High density
- C. Residential
- D. Standard office
Answer: A
Explanation:
A high-density deployment is a wireless network that is designed to support a large number of users and devices in a relatively small area. This type of deployment is often used in enterprise environments, such as offices, schools, and hospitals.
The use of semi-directional antennas in the deployment described in the question is a good indication that it is a high-density deployment. Semi-directional antennas can be used to focus the signal from an access point in a specific direction. This can help to reduce interference and improve performance in high-density environments.
The other answer choices are less likely to be correct for the following reasons:
* SOHO (small office/home office) deployments are typically smaller and less complex than high-density deployments.
* Residential deployments are typically even smaller and less complex than SOHO deployments.
* Standard office deployments may be high-density, but they may also be lower-density.
It is important to note that the type of deployment is not determined solely by the output power of the access points. However, the use of 10 mW of output power on the 2.4 GHz radios and 20 mW of output power on the
5GHz radios is also consistent with a high-density deployment.
Here are some additional tips for deploying a high-density wireless network:
* Use a site survey to determine the optimal placement of access points.
* Configure the access points to use non-overlapping channels.
* Use semi-directional or directional antennas to focus the signal and reduce interference.
* Implement a wireless intrusion prevention system (WIPS) to detect and mitigate rogue access points and other security threats.
NEW QUESTION # 72
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. The root bridge
- B. The Ethernet switch
- C. The RADIUS server
- D. All non-root bridges
Answer: A
Explanation:
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: Exam CWNA-
109], page 459; [Cisco Aironet Wireless Bridges FAQ], question 29.
NEW QUESTION # 73
When replacing the antenna of a WLAN device with a similar antenna type that has a higher passive gain, what antenna characteristic will decrease?
- A. Range
- B. Beamwidth
- C. Receive sensitivity
- D. Active gain
Answer: B
Explanation:
According to the CWNA Official Study Guide (CWNA-109), Chapter 4: Antennas and Accessories, antenna gain is a measure of how effectively an antenna focuses energy in a particular direction. When a passive antenna with a higher gain is used, it does not increase the transmitted power - instead, it focuses the RF energy more narrowly, creating a stronger signal in a smaller area.
"As the gain of an antenna increases, the beamwidth of the antenna decreases. This is because a higher gain antenna focuses energy more narrowly in one direction. While this increases range in that direction, it reduces coverage in other directions."
- CWNA-108 Study Guide, Chapter 4, Antenna Concepts and Beamwidth, p. 165-166 Thus, when you replace an antenna with one of higher passive gain, the beamwidth decreases while range in the direction of focus increases.
NEW QUESTION # 74
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. Site survey utility
- B. Spectrum analyzer
- C. WLAN scanner tool
- D. Protocol analyzer
Answer: C
Explanation:
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.
NEW QUESTION # 75
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 antennas in the laptop have insufficient gain to detect the 5 GHz signals.
- B. The clients are configured to use WPA and 5 GHz channels only support WPA2.
- C. The client drivers are faulty and should be upgraded.
- D. The access points are configured to disallow 5 GHz.
Answer: C
Explanation:
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
NEW QUESTION # 76
You are reporting on the RF environment in your facility. The manager asks you to describe the noise floor noted in the report. Which of the following is the best explanation?
- A. The energy radiated by flooring materials that causes interference in the 2.4 GHz and 5 GHz bands.
- B. The RF energy that exists in the environment from intentional and unintentional RF radiators that forms the baseline above which the intentional signal of your WLAN must exist.
- C. The extra energy radiated by access points and client devices beyond that intended for the signal.
- D. The noise caused by elevators, microwave ovens, and video transmitters.
Answer: B
Explanation:
The RF energy that exists in the environment from intentional and unintentional RF radiators that forms the baseline above which the intentional signal of your WLAN must exist is the best explanation of the noise floor noted in the report. The noise floor is a term that describes the level of background noise or interference in a wireless channel or band. The noise floor is measured in dBm (decibel-milliwatts) and it represents the minimum signal strength that can be detected or received by a wireless device. The noise floor is influenced by various factors, such as the sensitivity of the receiver, the antenna gain, the cable loss, and the ambient RF environment. The ambient RF environment consists of intentional and unintentional RF radiators that emit RF energy in the wireless spectrum. Intentional RF radiators are devices that are designed to transmit RF signals for communication purposes, such as Wi-Fi access points, Bluetooth devices, microwave ovens, or cordless phones. Unintentional RF radiators are devices that are not designed to transmit RF signals but generate electromagnetic radiation as a by-product of their operation, such as USB 3 devices, PC power supplies, or fluorescent lights. The noise floor affects WLAN performance and quality because it determines the minimum signal-to-noise ratio (SNR) that is required for a successful wireless transmission. SNR is the difference between the signal strength of the desired signal and the noise floor of the channel. SNR is also measured in dB and it indicates how much the signal stands out from the noise. A higher SNR means a better signal quality and a lower bit error rate. A lower SNR means a worse signal quality and a higher bit error rate.
Therefore, to achieve a reliable WLAN connection, the intentional signal of your WLAN must exist above the noise floor by a certain margin that depends on the data rate and modulation scheme used. The other options are not accurate or complete explanations of the noise floor noted in the report. The noise caused by elevators, microwave ovens, and video transmitters is not the noise floor but rather examples of interference sources that contribute to the noise floor. The extra energy radiated by access points and client devices beyond that intended for the signal is not the noise floor but rather an example of spurious emissions that cause interference to other devices or channels. The energy radiated by flooring materials that causes interference in the 2.4 GHz and 5 GHz bands is not the noise floor but rather an example of attenuation or reflection that reduces or changes the direction of the signal. References: CWNA-109 Study Guide, Chapter 5: Radio Frequency Signal and Antenna Concepts, page 139
NEW QUESTION # 77
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. DNS
- B. NTP
- C. BOOTH
- D. AP hosts file
Answer: A
Explanation:
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.
NEW QUESTION # 78
When compared with legacy Power Save mode, how does VHT TXOP power save improve battery life for devices on a WLAN?
- A. VHT TXOP power save allows stations to enter sleep mode and legacy Power Save does not.
- B. VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.
- C. VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.
- D. Legacy Power Save mode was removed in the 802.11ac amendment.
Answer: C
Explanation:
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.
NEW QUESTION # 79
You are reconfiguring an AP to use the short guard interval. How long will the new guard interval duration be after the change?
- A. 800 ns
- B. 104 ms
- C. 10 ms
- D. 400 ns
Answer: D
Explanation:
The short guard interval is an optional feature of 802.11n and 802.11ac that reduces the time between OFDM symbols from 800 ns to 400 ns. This can increase the data rate by about 11%, but also requires more precise timing and synchronization between the transmitter and the receiver. The short guard interval is only used when both the AP and the client support it and agree to use it . References: [CWNA-109 Study Guide], Chapter 4: Radio Frequency Signal and Antenna Concepts, page 163; [CWNA-109Study Guide], Chapter 4:
Radio Frequency Signal and Antenna Concepts, page 157.
NEW QUESTION # 80
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. 25.5 W
- B. 12.95 W
- C. 30 W
- D. 15.4 W
Answer: A
Explanation:
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.
NEW QUESTION # 81
What cipher suite is specified by the 802.11-2016 standard and is not deprecated?
- A. Extensible Authentication Protocol
- B. Wired Equivalent Privacy
- C. Temporal Key Integrity Protocol
- D. Counter Mode with CBC-MAC Pro tocol
Answer: D
Explanation:
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: ExamCWNA-109], page 295; [IEEE Standard for Information technology-Telecommunications and information exchange between systems Local and metropolitan area networks-Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications], page 1560.
NEW QUESTION # 82
What statement about 802.3, Clause 33 Power over Ethernet is true?
- A. Only endpoint PSEs are supported.
- B. The lowest voltage drop is achieved when using CAT6 cable instead of Cat5 or CAT5e.
- C. Only midspan PSEs are supported.
- D. When using CAT5 cabling, you increase the maximum draw available to the PD over that available with CAT6.
Answer: B
Explanation:
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
NEW QUESTION # 83
A client STA must choose the best AP for connectivity. As part of the evaluation, it must verify compatible data rates. What can the client STA use to verify that an AP supports the same data rates that it supports?
- A. Data frames sent between the AP and current clients STAs
- B. Authentication frames transmitted by the other client STAs
- C. Probe request frames transmitted by other client STAs
- D. Beacon frames transmitted by the AP
Answer: D
Explanation:
The client STA can use Beacon frames transmitted by the AP to verify that an AP supports the same data rates that it supports. Beacon frames are management frames that are periodically broadcasted by the APs to announce their presence, capabilities, and parameters. Oneof the information elements contained in the Beacon frames is the Supported Rates or Extended Supported Rates, which lists the data rates that the AP can use for communication. The client STA can compare its own data rates with those advertised by the AP to determine if they are compatible. Data frames, authentication frames, and probe request frames do not contain information about data rates. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 133; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 123.
NEW QUESTION # 84
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. The AP is improperly configured to use only 40 MHz of the 80 MHz allocated bandwidth
- B. All clients implement single spatial stream radios
- C. The clients are all 802.11n STAs or lower
- D. The short guard interval is also enabled
Answer: C
Explanation:
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, but only 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
NEW QUESTION # 85
What frame type is used to reserve the wireless medium for the transmission of high data rate frames that may not be understood by all clients connected to the BSS?
- A. Beacon
- B. ACK
- C. PS-Poll
- D. RTS
Answer: D
Explanation:
The frame type that is used to reserve the wireless medium for the transmission of high data rate frames that may not be understood by all clients connected to the BSS is RTS. RTS stands for Request to Send and is a control frame that is sent by a station to request access to the medium for a specified duration. The RTS frame contains the source and destination MAC addresses, as well as a Network Allocation Vector (NAV) value that indicates how long the medium will be occupied. The destination station responds with a Clear to Send (CTS) frame that echoes the NAV value and grants permission to the source station. All other stations in the BSS hear either the RTS or CTS frame and update their NAV timers accordingly, deferring their transmissions until the medium is free. The RTS/CTS mechanism can be used to prevent hidden node problems, reduce collisions, and protect high data rate frames that use features such as 802.11n or 802.11ac that may not be compatible with legacy stations. ACK, Beacon, and PS-Poll are not used to reserve the medium for high data rate frames. References: [CWNP Certified Wireless Network Administrator Official Study Guide: Exam CWNA-109], page 112; [CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-109], page 102.
NEW QUESTION # 86
You are a small business wireless network consultant and provide WLAN services for various companies. You receive a call from one of your customers stating that their laptop computers suddenly started experiencing much slower data transfers while connected to the WLAN. This company is located in a multi-tenant office building and the WLAN was designed to support laptops, tablets and mobile phones. What could cause a sudden change in performance for the laptop computers?
- A. The sky was not as cloudy that day as it typically is and the sun also radiates electromagnetic waves.
- B. A new tenant in the building has set their AP to the same RF channel that your customer is using.
- C. A few of your customer's users have Bluetooth enabled wireless headsets.
- D. The antennas in the laptops have been repositioned.
Answer: B
Explanation:
A possible cause of a sudden change in performance for the laptop computers is that a new tenant in the building has set their AP to the same RF channel that your customer is using. This can create co-channel interference (CCI), which is a situation where two or more APs or devices use the same or overlapping channels in the same area. CCI can degrade the performance of WLANs by increasing contention, collisions, retransmissions, and latency. CCI can also reduce the effective range and throughput of WLANs by lowering the signal-to-noise ratio (SNR). To avoid or mitigate CCI, it is recommended to use non-overlapping channels, adjust transmit power levels, or implement channel management techniques such as dynamic frequency selection (DFS) or load balancing. The sky condition, antenna position, or Bluetooth headset are not likely to cause a sudden change in performance for the laptop computers. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 81; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 71.
NEW QUESTION # 87
An 802.11 WLAN transmitter that emits a 50 mW signal is connected to a cable with 3 dB of loss. The cable is connected to an antenna with 16 dBi of gain. What is the power level at the Intentional Radiator?
- A. 500 mW
- B. 25 mW
- C. 250 mW
- D. 1000 mW
Answer: D
NEW QUESTION # 88
You are the network administrator for ABC Company. Your manager has recently attended a wireless security seminar. The seminar speaker taught that a wireless network could be hidden from potential intruders if you disabled the broadcasting of the SSID in Beacons and configured the access points not to respond to Probe Request frames that have a null SSID field.
Your manager suggests implementing these security practices. What response should you give to this suggestion?
- A. Any 802.11 protocol analyzer can see the SSID in clear text in frames other than Beacons frames. This negates any security benefit of trying to hide the SSID in Beacons and Probe Response frames.
- B. This security practice prevents manufacturers' client utilities from detecting the SSID. As a result, the SSID cannot be obtained by attackers, except through social engineering, guessing, or use of a WIPS.
- C. Any tenants in the same building using advanced penetration testing tools will be able to obtain the SSID by exploiting WPA EAPOL-Key exchanges. This poses an additional risk of exposing the WPA key.
- D. To improve security by hiding the SSID, the AP and client stations must both be configured to remove the SSID from association request and response frames. Most WLAN products support this.
Answer: A
Explanation:
The response that you should give to your manager's suggestion of implementing the security practices of disabling the broadcasting of the SSID in Beacons and configuring the access points not to respond to Probe Request frames that have a null SSID field is that any 802.11 protocol analyzer can see the SSID in clear text in frames other than Beacons frames. This negates any security benefit of trying to hide the SSID in Beacons and Probe Response frames. The SSID (Service Set Identifier) is a human-readable name that identifies a WLAN and allows users to connect to it. The SSID is transmitted in clear text in several types of 802.11 frames, such as Beacon frames, Probe Request frames, Probe Response frames, Association Request frames, Association Response frames, Reassociation Request frames, and Reassociation Response frames. Some people may think that hiding the SSID can improve the security of the WLAN by making it invisible to potential intruders. However, this is not true, as hiding the SSID only removes it from Beacon frames and Probe Response frames that have a null SSID field. The SSID is still present in other types of frames that can be easily captured and analyzed by any 802.11 protocol analyzer or wireless scanner tool. Therefore, hiding the SSID does not provide any real security benefit and may even cause some compatibility and performance issues for legitimate users. References: 1, Chapter 4, page 133; 2, Section 4.1
NEW QUESTION # 89
802. 11ax (HE) introduces Resource Units that can be used to allow communications with multiple devices at the same time, on the same channel, in the same BSS. What feature of 802.1 lax provides this functionality?
- A. TWT
- B. Wi-Fi-LTE
- C. 6 GHz support
- D. OFDMA
Answer: D
Explanation:
The feature of 802.11ax (HE) that provides this functionality is OFDMA. OFDMA stands for Orthogonal Frequency Division Multiple Access and is a technology that allows multiple devices to communicate simultaneously on the same channel in the same BSS. OFDMA works by dividing a channel into smaller subchannels called Resource Units (RUs), which are composed of groups of subcarriers or tones. Each RU can be assigned to a different device based on its bandwidth requirement and signal quality. This way, OFDMA can increase the efficiency and capacity of the channel by reducing overhead, contention, and latency.
OFDMA can also support both uplink and downlink multi-user transmissions using trigger frames and buffer status reports. 6 GHz support, TWT, and Wi-Fi-LTE are not features of 802.11ax that provide this functionality. References: [CWNP Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 226; [CWNA: Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 216.
NEW QUESTION # 90
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. Receive sensitivity
- D. Protocols utilized
Answer: B
Explanation:
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/
NEW QUESTION # 91
You administer a WLAN that offers a guest SSID of GUESTNWORK. Users connect to the GUESTNWORK SSID, but report that they cannot browse the Internet. The devices simply report no Internet connection. What common problem causes this scenario?
- A. Captive portal issues
- B. NTP issues
- C. IP routing issues
- D. Hardware issues
Answer: A
Explanation:
A common problem that causes this scenario is captive portal issues. A captive portal is a web page that requires users to authenticate or accept terms and conditions before accessing the Internet through a WLAN. A captive portal is often used for guest networks to provide security and control over the network access. A captive portal works by intercepting the user's web requests and redirecting them to the portal page until the user completes the required action. However, sometimes the captive portal may not work properly due to various reasons, such as browser settings, firewall rules, DNS configuration, or network errors. This can prevent the user from browsing the Internet or seeing the portal page. To troubleshoot captive portal issues, you can try to use a different browser, clear the browser cache andcookies, disable any VPN or proxy settings, manually enter the portal URL, or contact the network administrator. NTP issues, hardware issues, or IP routing issues are not common problems that cause this scenario. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 343; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 333.
NEW QUESTION # 92
......
Get CWNA-109 Actual Free Exam Q&As to Prepare Certification: https://examcollection.dumpsvalid.com/CWNA-109-brain-dumps.html