[Q28-Q51] Get 100% Passing Success With True CWNA-109 Exam! [Jul-2024]

NO.28 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?

NTP issues

Hardware issues

IP routing issues

Captive portal issues

NO.29 You administer a small WLAN with nine access point. As a small business, you do not rum a RADIUS server and use WPA2-Personal for security. Recently, you changed the passphrase for WPA2-personal in all Aps and clients. Several users are now reporting the inability to connect to the network at time and it is constrained to one area of the building. When using scanner, you see that the AP covering that area is online

The AP that covers the problem area requires a firmware update

The clients are improperly configured

The AP that covers the problem area has failed

The AP that covers the problem area is improperly configured

NO.30 What statement about 802.11 WLAN performance is true?

In modem networks, both centralized and distributed data forwarding work well for most standard office deployments

In most WLANs, no special skill or tuning is required to get peak performance

WLANs perform better as more wireless clients connect with each AP

To get the best performance out of an AP, you should disable data rates of 72 Mbps and lower

NO.31 What factors will have the most significant impact on the amount of wireless bandwidth available to each station within a BSS? (Choose 2)

The number of clientstations associated to the BSS

The power management settings in the access point’s beacons

The presence of co-located (10m away) access points on non-overlapping channels

The layer 3 protocol used by each station to transmit data over the wireless link

The factors that will have the most significant impact on the amount of wireless bandwidth available to each station within a BSS are:
* The number of client stations associated to the BSS
* The presence of co-located (10m away) access points on non-overlapping channels The number of client stations associated to the BSS affects the wireless bandwidth because each station shares the same channel and medium with other stations in the same BSS. The more stations there are, the more contention and collision there will be for the channel access, which reduces thethroughput and efficiency of the wireless communication. The wireless bandwidth available to each station depends on how the access point allocates the channel resources and how the stations use the channel time. For example, if the access point uses a round-robin scheduling algorithm, each station will get an equal share of the channel time regardless of its data rate or traffic demand. However, if the access point uses a proportional fair scheduling algorithm, each station will get a share of the channel time that is proportional to its data rate and traffic demand, which may result in higher or lower bandwidth for different stations.
The presence of co-located (10m away) access points on non-overlapping channels affects the wireless bandwidth because even though they use different channels, they may still cause interference and noise to each other due to channel leakage or imperfect filtering. The interference and noise can degrade the signal quality and SNR of the wireless communication, which reduces the data rate and throughput of the wireless communication. The wireless bandwidth available to each station depends on how well the access point and the station can cope with the interference and noise from other channels. For example, if the access point and the station support dynamic frequency selection (DFS) or adaptive radio management (ARM), they can switch to a less congested channel or adjust their output power or antenna gain to avoid or minimize interference from other channels.
References:1, Chapter 3, page 94;2, Section 3.2

NO.32 What is the most effective method for testing roaming in relation to 802.11 VoIP handsets?

Use a spectrum analyzer to monitor RF activity during a VoIP call.

Use a protocol analyzer to capture the traffic generated when a laptop roams.

Place a call with the handset and move around the facility to test quality during roaming.

Use the built-in roaming monitor built into all VoIP handsets.

NO.33 What facts are true regarding controllers and APs in a Split MAC architecture?

An IP tunnel is established between the AP and controller for AP management and control functions.

Using centralized data forwarding, APs never tag Ethernet frames with VLAN identifiers or 802.1p CoS.

With 802.1X/EAP security, the AP acts as the supplicant and the controller acts as the authenticator.

Management and data frame types must be processed locally by the AP, while control frame types must be sent to the controller.

NO.34 You are evaluating access points for use in the 5 GHz frequency band. What PHY supports this band and supports 80 MHz channels?

HT

VHT

ERP

OFDM

NO.35 You are implementing a VHT-capable AP. Which one of the following channels is available in the
802.11-2016 standard that was not available before the ratification of 802.11 ac?

56

161

153

144

NO.36 The center frequency of channel 1 in the 2.4 GHz band is 2.412 GHz (2412 MHz). What is the center frequency of channel 4?

2.427

2.422

2.413

2.417

NO.37 You are attempting to locate the cause of a performance problem in two WLAN cells in a mostly overlapping coverage area. You note that one AP is on channel 1 and the other is on channel 2. When you document your findings, what term do you use to describe the problem in this configuration?

CCI

CCC

ACI

Non-Wi-Fi interference

NO.38 You are implementing a multi-AP WLAN and fast secure roaming is essential. Which one of the following methods is an IEEE 802.11 standard method for fast roaming?

FT

OKC

Load balancing

Band steering

NO.39 What is an advantage of using WPA3-Personal instead of WPA2-Personal as a security solution for 802.11 networks?

WPA3-Personal, also called WPA3-SAE, uses an authentication exchange and WPA2-Personal does not

WPA3-Personal, also called WPA3-SAE, uses a stronger authentication exchange to better secure the network

WPA3-Personal, also called WPA3-SAE, uses AES for encryption and WPA2-Personal does not

WPA3-Personal, also called WPA3-SAE, uses a better encryption algorithm than WPA2-Personal

NO.40 Return Loss is the decrease of forward energy in a system when some of the power is being reflected back toward the transmitter. What will cause high return loss in an RF transmission system, including the radio, cables, connectors and antenna?

The use of 50 ohm cables longer than one meter in the RF system

High output power at the transmitter and use of a low-gain antenna

A significant impedance mismatch between components in the RF system

A Voltage Standing Wave Ratio (VSWR) of 1:1

NO.41 What feature of 802.1 lax (HE) is managed with beacon and trigger frames and is primarily a power management method, but also provides more efficient access to the channel used within a BSS?

TWT

BSS Color

UL-MU-MIMO

OFDMA

TWT is the feature of 802.11ax (HE) that is managed with beacon and trigger frames and is primarily a power management method, but also provides more efficient access to the channel used within a BSS. TWT stands for target wake time, which is a mechanism that allows an access point and a client device to negotiate and schedule specific times for data transmission and reception. This enables the client device to enter a low-power sleep mode when it is not expected to communicate with the access point, which saves battery life and reduces power consumption. TWT also reduces contention and interference on the channel used within a BSS, as it coordinates the transmissions of multiple client devices and avoids collisions. TWT is managed with beacon and trigger frames, which are two types of management frames that are used to announce and initiate data exchanges. A beacon frame is a frame that is periodically sent by an access point to advertise its presence, capabilities, and parameters to client devices. A trigger frame is a frame that is sent by an access point or a client device to request or initiate a data transmission with another device. BSS color, UL-MU-MIMO, and OFDMA are other features of 802.11ax (HE) that are not primarily power management methods, but rather performance enhancement methods. BSS color is a feature that assigns a color code to each BSS to differentiate it from other BSSs that use the same channel. This reduces interference and improves spatial reuse of the channel. UL-MU-MIMO is a feature that allows an access point to receive multiple simultaneous transmissions from different client devices using multiple spatial streams. This increases capacity and throughput of the uplink direction. OFDMA is a feature that divides a channel into smaller subchannels called resource units (RUs) that can be allocated to different devices for concurrent transmissions. This increases efficiency and flexibility of the channel utilization. References: CWNA-109 Study Guide, Chapter 10:
Wireless LAN Operation, page 323

NO.42 What authentication method is referenced in the 802.11-2016 and 802.11-2020 specifications and is recommended for robust WI-AN client security?

SSL

802.1X/EAP

IPSec

WEP

NO.43 A WLAN is implemented using wireless controllers. The APs must locate the controllers when powered on and connected to the network. Which one of the following methods is commonly used to locate the controllers by the APs?

NTP

DHCP

SNMP

GRE

NO.44 An RF signal sometimes bends as it passes through a material rather than around an obstacle. What is the RF behavior that this statement best describes?

Diffraction

Refraction

Scattering

Reflection

NO.45 What statement about the beamwidth of an RF antenna is true?

Horizontal and vertical beamwidth are calculated at the points where the main lobe decreases power by
3 dB.

The beamwidth patterns on an antenna polar chart indicate the point at which the RF signal stops propagating.

When antenna gain is lower, the beamwidth is also lower in both the horizontal and vertical dimensions.

Vertical beamwidth is displayed (in degrees) on the antenna’s Azimuth chart.

NO.46 When compared with legacy Power Save mode, how does VHT TXOP power save improve battery life for devices on a WLAN?

Legacy Power Save mode was removed in the 802.11ac amendment.

VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.

VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.

VHT TXOP power save allows stations to enter sleep mode and legacy Power Save does not.

NO.47 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?

The clients are configured to use WPA and 5 GHz channels only support WPA2.

The client drivers are faulty and should be upgraded.

The antennas in the laptop have insufficient gain to detect the 5 GHz signals.

The access points are configured to disallow 5 GHz.

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

NO.48 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?

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.

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.

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.

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.

NO.49 What statement about the IEEE 802.11-2016 QoS facility is true?

802.11 control frames are assigned to the 802.11 EF priority queue.

When the Voice queue has frames awaiting transmission, no data will be transmitted from the Best Effort queue.

802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention.

Four 802.1p user priorities are mapped to eight 802.11 transmit queues.

NO.50 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?

All clients implement single spatial stream radios

The clients are all 802.11n STAs or lower

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

The short guard interval is also enabled

NO.51 You must plan for POE in an office environment. Which one of these devices is least likely to be a POE PSE?

Midspan multi-port injector

Switch

VolP Phone

Midspan injector