CWAP-404 PDF問題集で2024年11月09日最近更新された問題
CWAP-404試験問題有効なCWAP-404問題集PDF
CWNP CWAP-404 認定試験の出題範囲：
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質問 # 30
What interframe space would be expected between a CIS and a Data frame?
- A. AIFS
- B. SIFS
- C. DIFS
- D. PIFS
正解：B
解説：
Explanation
The interframe space that would be expected between a CTS (Clear to Send) and a Data frame is SIFS (Short Interframe Space). A SIFS is the shortest interframe space that is used for high-priority transmissions, such as ACKs (Acknowledgements), CTSs, or data frames that are part of a fragmentation or aggregation process. A SIFS is a fixed value that depends on the PHY type and channel width. A CTS and a Data frame are part of a virtual carrier sense mechanism called RTS/CTS (Request to Send/Clear to Send), which is used to avoid collisions and hidden node problems in wireless transmissions. When a STA (station) wants to send a data frame, it first sends an RTS frame to the intended receiver, indicating the duration of the transmission. The receiver then responds with a CTS frame, also indicating the duration of the transmission. The other STAs in the vicinity hear either the RTS or the CTS frame and update their NAV (Network Allocation Vector) timers accordingly, deferring their access to the medium until the transmission is over. The sender then sends the data frame after waiting for a SIFS, followed by an ACK frame from the receiver after another SIFS. The other options are not correct, as they are not used between a CTS and a Data frame. A PIFS (PCF Interframe Space) is used for medium access by the PCF (Point Coordination Function), which is an optional and rarely implemented polling-based mechanism that provides contention-free service for time-sensitive traffic. An AIFS (Arbitration Interframe Space) is used for medium access by different ACs (Access Categories), which are logical queues that correspond to different QoS (Quality of Service) levels for different types of traffic. An AIFS is a variable interframe space that depends on the AIFSN (Arbitration Interframe Space Number) value of each AC. A DIFS (Distributed Interframe Space) is used for medium access by the DCF (Distributed Coordination Function), which is the default and mandatory contention-based mechanism that provides best-effort service for normal traffic. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 6: 802.11 Frame Exchanges, page 166-167; Chapter 7: QoS Analysis, page 194-195
質問 # 31
Which statements regarding an IEEE 802.11 Channel Switch Announcement frame are true?
(Choose 2)
- A. In an infrastructure BSS, Channel Switch Announcement frames may be transmitted by either the AP or an associated STA.
- B. Channel Switch Announcement frames are transmitted and retransmitted on a channel until all associated STAs successfully move to the new channel.
- C. Channel Switch Announcement frames are the only place where the Channel Switch Announcement element is found.
- D. Channel Switch Announcement elements may be carried in Beacon management frames.
- E. Channel Switch Announcement frames use the Action frame body format.
正解：D、E
質問 # 32
During an initial install of a controller-based WLAN, the APs are not locating the WLAN controller.
The controller is two router hops away from the nearest AP. DHCP is not used. When performing a packet trace, you see a DNS response code of 3 targeted at one of the APs.
What is the problem?
- A. The authentication to the DNS server failed
- B. The router is not forwarding packets to the DNS server
- C. The DNS server is not authoritative for the domain
- D. The controller host record has not been created in the DNS server
正解：D
質問 # 33
What is the function of the PMD sub-layer?
- A. Provides framing
- B. Adds a PHY preamble and header to a PSDU
- C. Converts 1s and 0s given to it by the PLCP sub-layer into the appropriate RF signals
- D. Performs A-MPDU
正解：C
質問 # 34
What is encrypted within the third message of the 4-Way Handshake?
- A. PTK
- B. GTK
- C. GMK
- D. PMK
正解：B
解説：
Explanation
The GTK (Group Temporal Key) is encrypted within the third message of the 4-Way Handshake. The 4-Way Handshake is a process that establishes a secure connection between a STA (station) and an AP (access point) using WPA2 (Wi-Fi Protected Access 2), which is a security protocol that uses AES-CCMP (Advanced Encryption Standard-Counter Mode CBC-MAC Protocol) as its encryption algorithm. The 4-Way Handshake consists of four messages that are exchanged between the STA and the AP. The first message is sent by the AP to the STA, containing the ANonce (Authenticator Nonce), which is a random number generated by the AP.
The second message is sent by the STA to the AP, containing the SNonce (Supplicant Nonce), which is a random number generated by the STA, and the MIC (Message Integrity Code), which is a value that verifies the integrity of the message. The third message is sent by the AP to the STA, containing the GTK, which is a key that is used to encrypt and decrypt multicast and broadcast data frames, and the MIC. The GTK is encrypted with the KEK (Key Encryption Key), which is derived from the PTK (Pairwise Temporal Key). The PTK is a key that is used to encrypt and decrypt unicast data frames, and it is derived from the PMK (Pairwise Master Key), the ANonce, and the SNonce. The fourth message is sent by the STA to the AP, containing only the MIC, to confirm the completion of the 4-Way Handshake. The other options are not correct, asthey are not encrypted within the third message of the 4-Way Handshake. The PMK is a key that is derived from a passphrase or obtained from an authentication server, and it is not transmitted in any message of the 4-Way Handshake. The PTK is a key that is derived from the PMK, the ANonce, and the SNonce, and it is not transmitted in any message of the 4-Way Handshake. The GMK (Group Master Key) is a key that is generated by the AP and used to derive the GTK, and it is not transmitted in any message of the 4-Way Handshake. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 8: Security Analysis, page 211-213
質問 # 35
ABC Company requires the ability to identify and quickly locate rogue devices. ABC has chosen an overlay WIPS solution with Wi-Fi sensors that use dipole antennas to perform this task. No other sensors are included. Use your knowledge of location tracking techniques to answer the question.
Which one of the following location methods is not available in the described system?
- A. Trilateration of RSSI measurements
- B. GPS Positioning
- C. RF Fingerprinting
- D. Time Difference of Arrival (TDoA)
正解：B
質問 # 36
What should the To DS and From DS flags be to set to in an Association Response frame?
- A. To DS = 1, From DS = 0
- B. To DS = 1, From DS = 1
- C. To DS = 0, From DS = 0
- D. To DS = 0, From DS = 1
正解：D
解説：
The To DS and From DS flags should be set to 0 in an Association Response frame. An Association Response frame is a type of management frame that is transmitted by an AP to accept or reject an association request from a STA. The To DS (To Distribution System) and From DS (From Distribution System) flags are two bits in the Frame Control field of the MAC header that indicate whether a frame is destined for or originated from the DS (Distribution System), which is a system that connects multiple BSSs together. The To DS and From DS flags can have four possible combinations: 00, 01, 10, or 11. For an Association Response frame, which is sent from an AP to a STA within a BSS, both flags should be set to 0.
質問 # 37
While at a government-operated facility, you are attempting to troubleshoot a WLAN performance problem using a wireless protocol analyzer. When you start capturing frames, you see a proprietary layer 2 protocol running over the ERP network as shown in this screenshot. The facility's WLAN administrator confirms that this protocol is proprietary and used for both data encryption and compression.
How will this information affect the steps you take to troubleshoot performance problems on this WLAN?
- A. Troubleshooting will be somewhat limited because only part of the information needed for performance measurements by the analyzer is encrypted. Each Data frame's MAC header will be encrypted, but the PLCP header can still be decoded successfully.
- B. As long as you load the proprietary software codec onto your analyzer computer, you will be able to see all of the Data frame information fully decoded. Loading the proprietary software codec will allow you to troubleshoot the WLAN as though no encryption were in use.
- C. The proprietary encryption protocol will have no effect on your troubleshooting steps because the wireless protocol analyzer can still decode the PLCP and MAC headers of Data frames. This situation is essentially no different than troubleshooting a WLAN that uses WPA2-Personal.
- D. In order to troubleshoot performance problems on a network using proprietary encryption protocols like this one, you must use a wireless protocol analyzer that has integrated support for the protocol in use.
正解：C
質問 # 38
Where would you look in a packet trace file to identify the configured Minimum Basic Rate (MBR) of a BSS?
- A. In the MBR Action frame
- B. Supported Rates & Extended Supported Rates elements in a Beacon frame
- C. In the MBR Information Element in an Association Response frame
- D. In the Minimum Basic Rate Element in a Beacon frame
正解：B
解説：
Explanation
The configured Minimum Basic Rate (MBR) of a BSS can be identified by looking at the Supported Rates and Extended Supported Rates elements in a Beacon frame. A Beacon frame is a type of management frame that is transmitted by an AP to advertise its presence and capabilities to potential clients. A Beacon frame contains various information elements (IEs) that provide details about the BSS configuration and operation. The Supported Rates andExtended Supported Rates IEs list the data rates that are supported by the AP for data transmission. The MBR is the lowest data rate among these supported rates that is required for all clients to join and communicate with the BSS. The MBR is usually marked with a flag bit in these IEs to indicate its mandatory status. The other options are not correct, as they do not exist or do not indicate the MBR of a BSS. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 5: 802.11 MAC Sublayer, page 123-124
質問 # 39
You have been asked to recommend a solution for protocol capture of 802.11 frames consisting of 3x3:3 802.11ac communications. The requirement specifies that you gain a general view of a coverage area and does not require that you capture from specific user locations. The solution must be the least expensive practical solution possible that does not disrupt user access to the WLAN and it must be based on enterprise WLAN hardware.
What solution would you recommend so that any coverage area could be monitored on demand?
- A. Install sufficient Aps so that an AP can be taken offline to perform protocol analysis as needed
- B. Install the minimum number of Aps required for coverage and use these Aps for protocol analysis as needed
- C. Install Wireshark on the Aps natively to allow dynamic capture while serving clients
- D. Install laptop-based protocol analyzer near each AP
正解：A
質問 # 40
Given: Protocol analyzer often have useful graphical dashboards providing information about the health and operations of the WLAN.
What is a valid use of a graph showing the Top APs Based on Active Associations?
- A. Ensuring compliance with corporate security policies
- B. Discovering the total number of client STAs on your network
- C. Locating overloaded APs
- D. Evaluating the capacity handling on a specific channel
正解：C
質問 # 41
Which one of the these is the most important in the WLAN troubleshooting methodology among those listed?
- A. Obtain detailed knowledge of the wireless vendors debug and logging options
- B. Talk to the end users about their experiences
- C. Observe the problem
- D. Interview the network manager about the issues being experienced
正解：C
解説：
Observing the problem is the most important step in the WLAN troubleshooting methodology among those listed. This step involves capturing and analyzing the relevant data from the wireless network, such as packets, frames, spectrum, and performance metrics. Observing the problem helps to verify the existence and scope of the issue, identify the root cause and possible solutions, and validate the results of any actions taken. The other steps are also important, but they are not as critical as observing the problem.
質問 # 42
You have installed a new 802.11ac WLAN configured with 80 MHz channels. Users in one area are complaining about poor performance. This area is currently served by a single AP. You take a spectrum analysis capture in the poor performing area. While examining the waterfall plot you notice the airtime utilization is higher on the first 20 MHz of the 80 MHz channel when compared to the rest of the channel. What do you conclude?
- A. The first 20 MHz is the AP's primary channel and higher airtime utilization on the primary channel is normal when an AP Is configured for 80 MHz operation
- B. The AP is misconfigured and needs to be reconfigured to 80MHz operation
- C. RRM is enabled and has dynamically picked a 20 MHz channel
- D. Non Wi-Fi interference is preventing the APs 80 MHz operation
正解：D
解説：
The most likely cause of higher airtime utilization on the first 20 MHz of the 80 MHz channel is non- Wi-Fi interference. Non-Wi-Fi interference can prevent an AP from using its full channel width, as it will degrade the signal quality and increase the noise floor on some parts of the channel. This will force the AP to fall back to a narrower channel width, such as 20 MHz or 40 MHz, to maintain communication with its clients. The waterfall plot can help identify non-Wi-Fi interference by showing spikes or bursts of RF energy on specific frequencies or sub-channels.
The other options are not correct, as they do not explain why only the first 20 MHz of the channel has higher airtime utilization.
質問 # 43
You are attempting to work through a user complaint with the CWNP-recommended troubleshooting methodology.
What must be clearly identified in order to reduce the number of possible causes at step three?
- A. The user name
- B. The user's IP configuration
- C. The problem
- D. The device type
正解：C
質問 # 44
What Interframe space would be expected between a CTS and a Data frame?
- A. AIFS
- B. SIFS
- C. DIFS
- D. PIFS
正解：B
解説：
The interframe space that would be expected between a CTS (Clear to Send) and a Data frame is SIFS (Short Interframe Space). A SIFS is the shortest interframe space that is used for high- priority transmissions, such as ACKs (Acknowledgements), CTSs, or data frames that are part of a fragmentation or aggregation process. A SIFS is a fixed value that depends on the PHY type and channel width. A CTS and a Data frame are part of a virtual carrier sense mechanism called RTS/CTS (Request to Send/Clear to Send), which is used to avoid collisions and hidden node problems in wireless transmissions. When a STA (station) wants to send a data frame, it first sends an RTS frame to the intended receiver, indicating the duration of the transmission. The receiver then responds with a CTS frame, also indicating the duration of the transmission. The other STAs in the vicinity hear either the RTS or the CTS frame and update their NAV (Network Allocation Vector) timers accordingly, deferring their access to the medium until the transmission is over. The sender then sends the data frame after waiting for a SIFS, followed by an ACK frame from the receiver after another SIFS. The other options are not correct, as they are not used between a CTS and a Data frame. A PIFS (PCF Interframe Space) is used for medium access by the PCF (Point Coordination Function), which is an optional and rarely implemented polling-based mechanism that provides contention-free service for time-sensitive traffic. An AIFS (Arbitration Interframe Space) is used for medium access by different ACs (Access Categories), which are logical queues that correspond to different QoS (Quality of Service) levels for different types of traffic. An AIFS is a variable interframe space that depends on the AIFSN (Arbitration Interframe Space Number) value of each AC. A DIFS (Distributed Interframe Space) is used for medium access by the DCF (Distributed Coordination Function), which is the default and mandatory contention-based mechanism that provides best-effort service for normal traffic.
質問 # 45
In a Spectrum Analyzer the Swept Spectrogram plot displays what information?
- A. RF power present at a particular frequency over the course of time
- B. Duty cycle in the frequency domain
- C. The RF time domain
- D. Wi-Fi Device information
正解：A
解説：
The Swept Spectrogram plot is a spectrum analysis plot that shows the RF power present at a particular frequency over the course of time. It can help identify trends and patterns in the RF spectrum over a longer period of time. It can also show how the RF environment changes over time and how different sources of RF signals affect each other. The other options are not correct, as they describe different types of plots or information that are not related to the Swept Spectrogram plot.
質問 # 46
You are concerned with management overhead in your WLAN. When evaluating the network, you note that each dual-band AP provides for 4 SSIDs in each band with three secure SSIDs and one Open System SSID. The network runs only 802.11ac APs and uses 20 MHz channels in 2.4 GHz and 400 MHz channels in 5 GHz.
What can you do to reduce the impact of beacon frames on CCI and channel utilization?
- A. Use only 40 MHz channels
- B. Disable SSID broadcasting
- C. Use the same security across all SSIDs
- D. Increase the beacon interval
正解：B
質問 # 47
Which one of the following is not a valid acknowledgement frame?
- A. Ack
- B. Block Ack
- C. CTS
- D. RTS
正解：D
解説：
Explanation
RTS is not a valid acknowledgement frame. RTS stands for Request To Send, and it is a control frame that is used to initiate an RTS/CTS exchange before sending a data frame. The purpose of an RTS/CTS exchange is to reserve the medium for a data transmission and avoid collisions with hidden nodes. An acknowledgement frame is a control frame that is used to confirm the successful reception of a data frame or a block of data frames. The valid acknowledgement frames are CTS (Clear To Send), Ack (Acknowledgement), and Block Ack (Block Acknowledgement) . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 186; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 187; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 189; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 190.
質問 # 48
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