CWNA-109ブレーン問題集PDF、CWNP CWNA-109試験問題豪華お試しセット [Q24-Q49]

CWNA-109ブレーン問題集PDF、CWNP CWNA-109試験問題豪華お試しセット

2024年最新されたCWNA-109サンプル問題は信頼され続けるCWNA-109テストエンジン

質問 # 24
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. Management and data frame types must be processed locally by the AP, while control frame types must be sent to the controller.
• D. With 802.1X/EAP security, the AP acts as the supplicant and the controller acts as the authenticator.

正解：A

解説：
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.

質問 # 25
You support a WLAN using dual-band 802.11ac three stream access points. All access points have both the
2.4 GHz and 5 GHz radios enabled and use 40 MHz channels in 5 GHz and 20 MHz channels in 2.4 GHz. A manager is concerned about the fact that each access point is connected using a 1 Gbps Ethernet link. He is concerned that the Ethernet link will not be able to handle the load from the wireless radios. What do you tell him?

• A. His concern is valid and the company should immediately plan to run a second 1 Gbps Ethernet link to each AP.
• B. Due to 802.11 network operations and the dynamic rates used by devices on the network, the two radios will likely not exceed the 1 Gpbs Ethernet link.
• C. His concern is invalid because the AP will compress all data before transmitting it onto the Ethernet link.
• D. His concern is valid and the company should upgrade all Ethernet links to 10 Gbps immediately.

正解：B

解説：
What you should tell him is that due to 802.11 network operations and the dynamic rates used by devices on the network, the two radios will likely not exceed the 1 Gbps Ethernet link. This is because the actual throughput of an 802.11 network is much lower than the theoretical data rates due to factors such as overhead, contention, interference, retransmissions, and environmental conditions. Moreover, the data rates used by devices on the network vary depending on their distance, signal quality, capabilities, and configuration.
Therefore, it is unlikely that both radios of the AP will simultaneously use the maximum data rates and saturate the 1 Gbps Ethernet link. Upgrading to a 10 Gbps Ethernet link or running a second 1 Gbps Ethernet link may be unnecessary and costly. Compressing all data before transmitting it onto the Ethernet link may introduce additional overhead and latency. References: [CWNP CertifiedWireless Network Administrator Official Study Guide: ExamCWNA-109], page 227; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 217.

質問 # 26
What factor does not influence the distance at which an RF signal can be effectively received?

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

正解：A

解説：
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.

質問 # 27
What statement describes the authorization component of a AAA implementation?

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

正解：B

解説：
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

質問 # 28
When antenna gain is reported in dBi, the gain of the antenna is compared to what theoretical radiator?

• A. Anthropomorphic radiator
• B. Dipole radiator
• C. End-fire radiator
• D. Isotropic radiator

正解：D

解説：
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

質問 # 29
In a mesh BSS (MBSS), according to the 802.11 standard, what device connect the mesh to an Ethernet network?

• A. Mesh Gate
• B. Mesh Portal
• C. Mesh Router
• D. Mesh Switch

正解：B

解説：
a mesh portal is a device that connects a mesh BSS (MBSS) to an Ethernet network, such as the Internet. A mesh portal acts as a bridge between the wired and wireless domains, and allows the mesh stations to communicate with external networks. A mesh portal is also a mesh point, which means it can forward traffic within the MBSS.
The other options are not correct. Option A. Mesh Gate is a device that connects a mesh BSS (MBSS) to another mesh BSS or another wireless network, such as an infrastructure BSS or an ad hoc network2. A mesh gate acts as a gateway between different wireless domains, and allows the mesh stations to communicate with other wireless networks. A mesh gate is also a mesh point, which means it can forward traffic within the MBSS. Option B. Mesh Switch is not a valid term in the 802.11 standard. Option C. Mesh Router is also not a valid term in the 802.11 standard.

質問 # 30
A client complains of low data rates on his computer. When you evaluate the situation, you see that the signal strength is -84 dBm and the noise floor is -96 dBm. The client is an 802.11ac client and connects to an
802.11ac AP. Both the client and AP are 2x2:2 devices. What is the likely cause of the low data rate issue?

• A. Weak signal strength
• B. Too few spatial streams
• C. CAT5e cabling run to the AP
• D. Lack of support for 802.11n

正解：A

解説：
Weak signal strength is the likely cause of the low data rate issue for the client that has a signal strength of -84 dBm and a noise floor of -96 dBm. The client is an 802.11ac client and connects to an 802.11ac AP. Both the client and AP are 2x2:2 devices. Signal strength is the measure of how strong the RF signal is at the receiver.
Signal strength can affect the reliability and performance of the wireless connection, as well as the data rate and throughput of the traffic. The higher the signal strength, the better the signal quality and the higher the data rate. The lower the signal strength, the worse the signal quality and the lower the data rate.
The data rate of an 802.11ac connection depends on several factors, such as channel bandwidth, modulation and coding scheme (MCS), spatial streams, guard interval, and beamforming. However, these factors are also influenced by the signal strength, as they require a certain signal-to-noise ratio (SNR) to operate properly.
SNR is the ratio of the signal strength to the noise floor, which is the measure of the background noise or interference in the RF environment. The higher the SNR, the more robust and efficient the communication.
The lower the SNR, the more prone and vulnerable to errors and retries.
According to the CWNA Official Study Guide , Table 3.7, page 112, an 802.11ac connection with a channel bandwidth of 80 MHz, an MCS of 9, two spatial streams, a short guard interval, and no beamforming can achieve a maximum data rate of 867 Mbps. However, this data rate requires a minimum SNR of 30 dB to maintain a sufficient signal quality. If the signal strength is -84 dBm and the noise floor is -96 dBm, then the SNR is only 12 dB (-84 dBm - (-96 dBm) = 12 dB), which is far below the required SNR for this data rate.
Therefore, the data rate will drop significantly to match the lower SNR and signal quality.
To solve this problem, the signal strength should be increased to improve the SNR and data rate. This can be done by adjusting the output power or channel assignment of the AP or client, relocating or reorienting some APs or antennas to reduce attenuation or interference, updating or replacing some faulty oroutdated hardware or software components, etc. References: , Chapter 3, page 112; , Section 3.2

質問 # 31
The IEEE 802.11-2012 standard requires VHT capable devices to be backward compatible with devices using which other 802.11 physical layer specifications (PHYs)?

• A. DSSS-OFDM
• B. ERP-PBCC
• C. HR/DSSS
• D. OFDM

正解：D

解説：
OFDM (Orthogonal Frequency Division Multiplexing) is the physical layer specification (PHY) that VHT capable devices must be backward compatible with according to the IEEE 802.11-2012 standard. VHT (Very High Throughput) is aPHY and MAC enhancement that is defined in the IEEE 802.11ac amendment and is also known as Wi-Fi 5. VHT operates only in the 5 GHz band and uses features such as wider channel bandwidths (up to 160 MHz), higher modulation schemes (up to 256-QAM), more spatial streams (up to eight), multi-user MIMO (MU-MIMO), beamforming, and VHT PHY and MAC enhancements. VHT can achieve data rates up to 6.9 Gbps.
According to the IEEE 802.11-2012 standard, VHT capable devices must be backward compatible with devices using OFDM PHY, which is defined in the IEEE 802.11a amendment and is also used by IEEE
802.11g, IEEE 802.11n, and IEEE 802.11h amendments. OFDM operates in both the 2.4 GHz and 5 GHz bands and uses features such as subcarriers, symbols, guard intervals, and OFDM PHY and MAC enhancements. OFDM can achieve data rates up to 54 Mbps.
Backward compatibility means that VHT capable devices can interoperate with OFDM devices on the same network by using common features and parameters that are supported by both PHYs. For example, VHT capable devices can use a channel bandwidth of 20 MHz, a modulation scheme of BPSK, QPSK, or 16-QAM, one spatial stream, no beamforming, and OFDM PHY and MAC headers when communicating with OFDM devices. Backward compatibility also means that VHT capable devices can fall back to OFDMmode when the signal quality or SNR is too low for VHT mode. References: 1, Chapter 3, page 123; 2, Section 3.2

質問 # 32
Which one of the following is not a factor considered when calculating the Link Budget for an outdoor point-to- point WLAN bridge link?

• A. Receive antenna gain
• B. Operating frequency
• C. Transmit power
• D. MU-MIMO capabilities of the bridges

正解：D

解説：
MU-MIMO capabilities of the bridges are not a factor considered when calculating the Link Budget for an outdoor point-to-point WLAN bridge link. The Link Budget is acalculation of the expected signal strength at the receiver based on various factors that affect the RF transmission. Some of these factors are operating frequency, transmit power, receive antenna gain, free space path loss, cable loss, connector loss, and environmental loss. MU-MIMO stands for Multi-User Multiple Input Multiple Output, which is a technology that allows multiple devices to communicate simultaneously using multiple spatial streams. MU-MIMO is not relevant for a point-to-point link, where there are only two devices involved. References: 1, Chapter 2, page
59; 2, Section 2.2

質問 # 33
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. uplink MU-MIMO
• B. 6 GHz band support
• C. TWT
• D. BSS Color

正解：D

解説：
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.

質問 # 34
What statement is true concerning the use of Orthogonal Frequency Division Multiplexing (OFDM) modulation method in IEEE 802.11 WLANs?

• A. OFDM implements BPSK modulation to allow for data rates up to 7 Gbps.
• B. OFDM was used by Frequency Hopping Spread Spectrum (FHSS) PHY devices.
• C. OFDM was first introduced in 802.11a and is used by the ERP, HT and VHT PHYs as well.
• D. OFDM modulation is used only in 5 GHz 802.11 transmissions.

正解：C

解説：
OFDM is a modulation method that divides the channel bandwidth into multiple subcarriers, each carrying a single data symbol. This allows for higher data rates and more robust transmissions in multipath environments.
OFDM was first introduced inthe 802.11a standard, which operates in the 5 GHz band and supports data rates up to 54 Mbps. Later, the 802.11g standard adopted OFDM for the 2.4 GHz band, and the 802.11n and
802.11ac standards enhanced OFDM with features such as MIMO (Multiple Input Multiple Output), channel bonding, and higher-order modulation schemes to achieve data rates up to 600 Mbps and 6.9 Gbps, respectively. These standards are collectively known as the ERP (Extended Rate PHY), HT (High Throughput), and VHT (Very High Throughput) PHYs . 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.

質問 # 35
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 few of your customer's users have Bluetooth enabled wireless headsets.
• C. A new tenant in the building has set their AP to the same RF channel that your customer is using.
• D. The antennas in the laptops have been repositioned.

正解：C

解説：
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.

質問 # 36
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. 30 W
• C. 15.4 W
• D. 12.95 W

正解：A

解説：
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.

質問 # 37
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. HTTP is in use instead of HTTPS
• C. WPA2 is disabled on the WLAN
• D. A VPN with the AP is not established

正解：B

解説：
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?].

質問 # 38
What 802.11 PHY uses available space in very low frequency ranges that is not in use at the time by broadcast video signals?

• A. DMG
• B. TVHT
• C. DSSS
• D. SIG

正解：B

解説：
TVHT stands for Television Very High Throughput and it is a PHY defined by the 802.11af amendment. It uses the TV white space (TVWS) spectrum in the VHF and UHF bands between 54 and 790 MHz, which are not in use by broadcast video signals at the time. It can provide long-range and low-power connectivity for WLAN devices.

質問 # 39
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. Authentication frames transmitted by the other client STAs
• B. Beacon frames transmitted by the AP
• C. Probe request frames transmitted by other client STAs
• D. Data frames sent between the AP and current clients STAs

正解：B

解説：
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.

質問 # 40
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. WPA3-Enterprise
• B. WPA3-SAE
• C. OWE
• D. Kerberos

正解：C

質問 # 41
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. PS-Poll
• B. ACK
• C. Beacon
• D. RTS

正解：D

解説：
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:
ExamCWNA-109], page 112; [CWNA: Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 102.

質問 # 42
ABC Company is planning to install a new 802.11ac WLAN, but wants to upgrade its wired infrastructure first to provide the best user experience possible. ABC Company has hired you to perform the RF site survey.
During the interview with the network manager, you are told that the new Ethernet edge switches will support VoIP phones and 802.11 access points, both using 802.3 PoE.
After hearing this information, what immediate concerns do you note?

• A. The edge Ethernet switches should support Ether-channel to get the best results out of the network.
• B. The power budget in the edge switches must be carefully planned and monitored based on the number of supported PoE devices.
• C. VoIP phones and 802.11 access points should not be powered by the same edge switch due to distortion.
• D. If the switches are in optimal locations for VoIP phones, they are likely to be suboptimal locations for
  802.11 APs

正解：B

解説：
An immediate concern that you note after hearing this information is that the power budget in the edge switches must be carefully planned and monitored based on the number of supported PoE devices. PoE stands for Power over Ethernet and is a technology that allows Ethernet switches to deliver power along with data to devices such as VoIP phones and 802.11 access points. PoE devices are classified into different classes based on their power consumption and output. The edge switches have a limited power budget that determines how many PoE devices they can support simultaneously. If the power budget is exceeded, some PoE devices may not receive enough power or may shut down unexpectedly. Therefore,it is important to plan and monitor the power budget in the edge switches based on the number and class of PoE devices connected to them. Using Ether-channel, placing switches in optimal locations, or avoiding distortion are not immediate concerns related to PoE devices. References: [CWNP Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 234; [CWNA: Certified Wireless Network Administrator Official Study Guide:
ExamCWNA-109], page 224.

質問 # 43
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. Airtime utilization
• B. Channel occupied
• C. Receive sensitivity
• D. Protocols utilized

正解：A

解説：
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/

質問 # 44
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. NTP issues
• B. IP routing issues
• C. Captive portal issues
• D. Hardware issues

正解：C

解説：
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.

質問 # 45
What statement about 802.11 WLAN bridges is true?

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

正解：D

解説：
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.

質問 # 46
What statement about the beamwidth of an RF antenna is true?

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

正解：B

解説：
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

質問 # 47
You are deploying a WLAN monitoring solution that utilizes distributed sensor devices. Where should sensors be deployed for best results? Choose the single best answer.

• A. Every 5 meters and alongside each AP
• B. Above the plenum on each floor
• C. In switching closets
• D. In critical areas where WLAN performance must be high

正解：D

解説：
Sensors should be deployed in critical areas where WLAN performance must be high for best results when using a WLAN monitoring solution that utilizes distributed sensor devices. A WLAN monitoring solution is a system that collects, analyzes, and reports on the status and performance of a WLAN. A WLAN monitoring solution can use different methods to gather data from the WLAN, such as embedded software agents, external hardware probes, or distributed sensor devices. Distributed sensor devices are dedicated devices that are deployed throughout the WLAN coverage area to monitor the wireless traffic and environment. Distributed sensor devices can perform various functions, such as scanning the spectrum, capturing wireless frames, measuring signal quality, detecting rogue access points, testing connectivity, and generating alerts. Distributed sensor devices can provide more accurate and comprehensive data than other methods, but they also require more planning and deployment costs. Therefore, it is important to deploy sensors strategically in critical areas where WLAN performance must be high, such as high-density zones, high-priority applications, or high-security locations. By deploying sensors in critical areas, the WLAN monitoring solution can ensure optimal WLAN performance and reliability in those areas and identify and resolve any issues or problems that may arise. The other options are not the best places to deploy sensors for best results. Deploying sensors in switching closets is not effective because sensors need to be close to the wireless medium to monitor it properly. Deploying sensors every 5 meters and alongside each AP is not efficient because sensors may overlap or interfere with each other and cause unnecessary redundancy or complexity. Deploying sensors above the plenum oneach floor is not practical because sensors may not capture the wireless traffic and environment accurately due to attenuation or reflection from the ceiling materials or objects. References: CWNA-109 Study Guide, Chapter 14: Troubleshooting Wireless LANs, page 4831

質問 # 48
What security option for 802.11 networks supports SAE and requires protected management frames?
* WPA

• A. WPA3
• B. WPA2
• C. OWE

正解：C

解説：
The security option for 802.11 networks that supports SAE and requires protected management frames is WPA3. WPA3 stands for Wi-Fi Protected Access version 3 and is the latest security standard for WLANs.
WPA3 supports two modes: WPA3-Personal and WPA3-Enterprise. WPA3-Personal uses Simultaneous Authentication of Equals (SAE) as the key exchange protocol, which provides stronger protection against offline dictionary attacks and password guessing than WPA2-Personal. WPA3 also requires protected management frames, which are encrypted frames that prevent spoofing, replay, or denial-of-service attacks on management frames such as deauthentication or disassociation frames. WPA, WPA2, and OWE do not support SAE or require protected management frames. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 307; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 297.

質問 # 49
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