CWNP CWNA-109 Online Practice Questions and Exam Preparation

CWNP CWNA-109 Online Questions & Answers

• Question 61:

  In which plane of the three networking planes is an access point configured by a WLAN controller?

  A. Control
  B. Management
  C. Security
  D. Data
  B. Management

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  Explanation/Reference:

  An access point is configured by a WLAN controller in the management plane of the three networking planes. The management plane is responsible for the configuration, administration, and monitoring of network devices, such as access points, switches, routers, and controllers. The WLAN controller communicates with the access point using a management protocol, such as CAPWAP or SNMP, to send configuration commands and receive status information. The control plane is responsible for the routing, switching, and forwarding of network traffic, such as data frames and control frames. The WLAN controller may also participate in the control plane by performing functions such as authentication, encryption, roaming, and load balancing. The security plane is responsible for the protection of network devices and data from unauthorized access, modification, or disclosure. The WLAN controller may also participate in the security plane by implementing features such as firewall, VPN, IDS/IPS, and WIPS. The data plane is responsible for the transmission and reception of user data, such as voice, video, or web traffic. The WLAN controller may or may not participate in the data plane depending on the architecture of the WLAN. In some cases, the access point forwards the user data directly to the wired network without involving the WLAN controller (distributed data forwarding). In other cases, the access point tunnels the user data to the WLAN controller before forwarding it to the wired network (centralized data forwarding). References: CWNA-109 Study Guide, Chapter

  9: Wireless LAN Architecture, page 279

• Question 62:

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

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  Explanation/Reference:

  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

• Question 63:

  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. RTS
  B. ACK C. Beacon
  D. PS-Poll
  A. RTS

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  Explanation/Reference:

  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.

• Question 64:

  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 power budget in the edge switches must be carefully planned and monitored based on the number of supported PoE devices.
  B. The edge Ethernet switches should support Ether-channel to get the best results out of the network.
  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
  A. The power budget in the edge switches must be carefully planned and monitored based on the number of supported PoE devices.

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  Explanation/Reference:

  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.

• Question 65:

  When implementing PoE, what role is played by a switch?

  A. PSE
  B. Midspan injector
  C. PD
  D. Power splitter
  A. PSE

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  Explanation/Reference:

  PoE stands for Power over Ethernet, which is a technology that allows network devices to receive power and data over the same Ethernet cable. PoE eliminates the need for separate power adapters or outlets for devices such as IP phones, cameras, or APs. PoE requires two types of devices: PSE (Power Sourcing Equipment) and PD (Powered Device). A PSE is a device that provides power to the Ethernet cable, such as a switch, injector, or splitter. A PD is a device that receives power from the Ethernet cable, such as an IP phone, camera, or AP. When implementing PoE, a switch plays the role of a PSE910. References: CWNA-109 Study Guide, Chapter 7: Power over Ethernet (PoE), page 293; CWNA109Study Guide, Chapter 7: Power over Ethernet (PoE), page 287.

• Question 66:

  Which unit of measurement, as formally defined, is an absolute unit that is used to quantify received signal power levels on a logarithmic scale?

  A. SNI
  B. VSWR
  C. dBm
  D. dBi
  C. dBm

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  Explanation/Reference:

  The unit of measurement that is an absolute unit and is used to quantify received signal power levels on a logarithmic scale is dBm. dBm stands for decibel-milliwatt and represents the power level relative to 1 milliwatt (mW). dBm is an absolute unit because it has a fixed reference point and does not depend on the input power level. dBm is used to measure the received signal power levels on a logarithmic scale because it can express large variations in power levels with small numbers and make calculations easier. For example, a 10 dB increase in power level means a 10-fold increase in power, and a 20 dB increase means a 100-fold increase in power. References: [CWNP Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 66; [CWNA: Certified Wireless Network Administrator Official Study Guide: ExamCWNA-109], page 56.

• Question 67:

  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

  A. The AP that covers the problem area requires a firmware update
  B. The clients are improperly configured
  C. The AP that covers the problem area has failed
  D. The AP that covers the problem area is improperly configured
  B. The clients are improperly configured

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  Explanation/Reference:

  This is because the passphrase for WPA2-Personal is case-sensitive and must match exactly on both the AP and the client. If the passphrase is entered incorrectly on the client, the client will not be able to authenticate with the AP and connect to the network. The AP that covers the problem area is not likely to require a firmware update, fail, or be improperly configured, as it is online and works with other clients that have the correct passphrase. To troubleshoot this issue, you can check the passphrase settings on the clients and make sure they matchwith the AP. You can also try to reconnect the clients to the network or reboot them if necessary. For more information on how to configure WPA2-Personal on your router

• Question 68:

  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 first introduced in 802.11a and is used by the ERP, HT and VHT PHYs as well.
  C. OFDM modulation is used only in 5 GHz 802.11 transmissions.
  D. OFDM was used by Frequency Hopping Spread Spectrum (FHSS) PHY devices.
  B. OFDM was first introduced in 802.11a and is used by the ERP, HT and VHT PHYs as well.

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  Explanation/Reference:

  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.

• Question 69:

  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. OWE
  B. Kerberos
  C. WPA3-Enterprise
  D. WPA3-SAE
  A. OWE

• Question 70:

  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?

  A. FT
  B. OKC
  C. Load balancing
  D. Band steering
  A. FT

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  Explanation/Reference:

  FT (Fast Transition) is an IEEE 802.11 standard method for fast roaming. FT is defined in the IEEE 802.11r amendment and is also known as Fast BSS Transition (FBT) or Fast Secure Roaming. FT is a feature that allows a client station to quickly switch from one AP to another within the same ESS (Extended Service Set) without having to re-authenticate and re-associate with each AP. This reduces the latency and packet loss that may occur during roaming, thus improving the user experience and maintaining the security of the connection. FT works by using pre-authentication and key caching mechanisms that allow the client station and the APs to exchange security information before the actual roaming occurs. This way, when the client station decides to roam to a new AP, it can use a fast reassociation request and response that contain only a few fields, instead of a full authentication and association exchange that require more time and data. References: 1, Chapter 9, page 367; 2, Section 6.3