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?
Correct Answer: B
Refraction is the bending of an RF signal as it passes through a material of different density. Refraction can cause the signal to change its direction and angle of arrival. For example, when a light beam passes from air to water, it bends because of the difference in the refractive index of the two mediums. Similarly, when an RF signal passes from one medium to another, such as from air to glass, it can bend due to the change in the dielectric constant of the materials12. References: 1:CWNA-109Official Study Guide, page 67 2: Refraction
CWNA-109 Exam Question 12
Three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. Assuming no other APs are in the vicinity, is CCI still a possibility in this network and why?
Correct Answer: A
CCI is still a possibility in this network because the client devices connected to one of the channel 1 APs will transmit frames that reach the other channel 1 AP as well as clients connected to the other channel 1 AP. CCI stands for co-channel interference, which is a type of interference that occurs when two or more devices transmit on the same channel within range of each other. CCI reduces performance and capacity because it causes contention and collisions on the wireless medium, which leads to retransmissions and delays. CCI can be mitigated by increasing physical separation between devices using the same channel or byreducing transmit power levels to limit coverage area. In this scenario, three access points are used within a facility. One access point is on channel 11 and the other two are on channel 1. The two access points using channel 1 are on either side of the access point using channel 11 and sufficiently apart so that they do not interfere with each other when they transmit frames. However, this does not prevent CCI from occurring between their client devices that are connected on channel 1. For example, if a client device connected to one of the channel 1 APs sends a frame to another device on the wired network or on another wireless network (such as an Internet server or a VoIP phone), that frame will be heard by both channel 1 APs as well as any other client devices connected to either of them on channel 1. This will cause CCI because these devices will have to wait for the channel to be clear before they can transmit their own frames. The answer that CCI only occurs in the 5 GHz frequency band is incorrect; CCI can occur in any frequency band where devices use the same channel. The answer that channel 11 loops around and causes CCI with channel 1 is also incorrect; channel 11 does not loop around and it operates in a different frequency band than channel 1. References: CWNA-109 Study Guide, Chapter 5: Radio Frequency Signal and Antenna Concepts, page 147
CWNA-109 Exam Question 13
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?
Correct Answer: A
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.
CWNA-109 Exam Question 14
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?
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.
CWNA-109 Exam Question 15
What security option for 802.11 networks supports SAE and requires protected management frames? * WPA
Correct Answer: C
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.