CWNA-109 Online Practice Questions and Answers

Correct Answer: A

In a public Wi-Fi hotspot, like the one Lynne runs in his hotel, ensuring customer security against active attacks is crucial. Active attacks involve unauthorized access, eavesdropping, or manipulation of the network traffic. To mitigate such

threats, an effective and practical step is:

Station-to-Station Traffic Blocking: Also known as client isolation, this feature prevents direct communication between devices connected to the Wi-Fi network. By enabling this on the access points, Lynne can significantly decrease the

likelihood of active attacks like man-in-the-middle (MITM) attacks, where an attacker intercepts and possibly alters the communication between two parties. The other options, while beneficial for network security, might not be as

straightforward or practical for Lynne's situation:

Network Access Control (NAC)requires a more complex infrastructure and management, which might not be ideal for a small hotel setup. Implementing an SSL VPNadds an extra layer of security but might complicate the login process for

users, potentially affecting the user experience. Requiring EAP-FAST authenticationprovides secure authentication but may not be feasible for transient customers who expect quick and easy network access. Therefore, enabling station-tostation traffic blocking is a practical and efficient measure that Lynne can implement to enhance customer security on the Wi-Fi network.

References:

CWNA Certified Wireless Network Administrator Official Study Guide:

ExamCWNA-109, by David D. Coleman and David A. Westcott. Best practices for securing a wireless network in a public hotspot environment.

Correct Answer: D

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.

Correct Answer: A

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

Correct Answer: D

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.

Correct Answer: D

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.

Correct Answer: D

VSWR stands for Voltage Standing Wave Ratio, which is a measure of how well the impedance of the RF cable and connectors matches the impedance of the transmitter and the antenna. Impedance is the opposition to the flow of alternating current in an RF circuit, and it depends on the frequency, resistance, capacitance, and inductance of the components. A perfect impedance match would have a VSWR of 1:1, meaning that all the power is transferred from the transmitter to the antenna, and none is reflected back. However, in reality, there is always some degree of mismatch, which causes some power to be reflected back to the transmitter, creating standing waves along the cable. This reduces the efficiency and performance of the wireless system, and can also damage the transmitter. Excessive VSWR can be caused by using poor quality or damaged cables and connectors, or by using components that have different impedance ratings123. References: CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 90; CWNA-109Study Guide, Chapter 2: Radio Frequency Fundamentals, page 86; CWNP website, CWNA Certification.

Correct Answer: C

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/

Correct Answer: A

Correct Answer: C

https://www.wlanmall.com/what-is-a-wireless-bridge/ Wireless bridging is a WLAN technology role that allows two or more networks to be connected wirelessly over a distance. A wireless bridge consists of two or more APs that are configured to operate in bridge mode and use directional antennas to establish a point- to-point or point-to-multipoint link. Wireless bridging can support high data rates and is suitable for scenarios where running cables is impractical or expensive. To create a wireless link between two buildings on a single campus that supports at least 150 Mbps data rates, wireless bridging is an appropriate solution678. References: CWNA-109 Study Guide, Chapter 6: Wireless LAN Devices and Topologies, page 271; CWNA-109Study Guide, Chapter 6: Wireless LAN Devices and Topologies, page 265; Wi-Fi Wireless Bridging Explained.

Correct Answer: C

A BSS (Basic Service Set) is a WLAN use case that represents an 802.11- based network that uses an AP (Access Point) and has several connecting clients. The AP acts as a central point of coordination and communication for the clients, which can include iPhones, iPads, laptops, desktops, or any other devices that have Wi-Fi capabilities. A BSS can be identified by a unique BSSID (Basic Service Set Identifier), which is usually the MAC address of the AP's radio interface. A BSS can also be associated with an SSID (Service Set Identifier), which is a human-readable name that identifies the network. References: , Chapter 1, page 23; , Section 1.1