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CWNP CWAP-404 Exam Certification Details:
| Exam Price | $275 USD |
| Number of Questions | 60 |
| Exam Registration | PEARSON VUE |
| Passing Score | 70% |
| Sample Questions | CWNP CWAP-404 Sample Questions |
NEW QUESTION # 22
Which one of the following portions of information is communicated by bits in the PHY Header?
- A. Signal strength
- B. SNR
- C. Noise
- D. Data rate
Answer: D
Explanation:
Explanation
One of the information that is communicated by bits in the PHY header is data rate. Data rate is the speed at which data is transmitted or received over the wireless medium. Data rate depends on factors such as modulation, coding, channel width, spatial streams, and guard interval. Data rate is indicated by bits in different fields of the PHY header, depending on the type of PPDU (e.g., OFDM, HT, VHT, HE). The receiver uses these bits to determine how to decode and demodulate the rest of the PPDU. The other options are not correct, as they are not communicated by bits in the PHY header. SNR (Signal-to-Noise Ratio), noise, and signal strengthare measured by the receiver based on its own capabilities and environment. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 4: 802.11 Physical Layer, page 101-105
NEW QUESTION # 23
What is an AIFS?
- A. The shortest period of time a STA can sleep
- B. A variable Interframe Space introduced by 802.lie to help prioritize medium access for different Access Categories
- C. A medium access method introduced by 802.lln, but never implemented
- D. A form of aggregation performed at the PHY layer based on 802.lie UP values interpreted from DSCP values
Answer: B
Explanation:
Explanation
An AIFS is a variable interframe space introduced by 802.11e to help prioritize medium access for different Access Categories (ACs). An interframe space is a period of time that a STA (station) has to wait before attempting to access the medium. An AIFS is a type of interframe space that varies depending on the AC of the traffic. An AC is a logical queue that corresponds to a QoS (Quality of Service) level for different types of traffic. There are four ACs defined by 802.11e: AC_VO (Voice), AC_VI (Video), AC_BE (Best Effort), and AC_BK (Background). Each AC has a different AIFSN (Arbitration Interframe Space Number) value, which determines how long it has to wait before attempting to access the medium. A lower AIFSN value means a higher priority and a shorter waiting time. The other options are not correct, as they do not describe what an AIFS is. An AIFS is not a medium access method introduced by 802.11n, but never implemented, as it is part of the 802.11e standard and widely used in QoS-enabled WLANs. An AIFS is not a form of aggregation performed at the PHY layer based on 802.11e UP values interpreted from DSCP values, as aggregation is a technique that combines multiple frames into one larger frame to improve efficiency and throughput, not prioritization or medium access. An AIFS is not the shortest period of time a STA can sleep, as sleeping is a power saving mode that allows a STA to conserve battery power by periodically turning off its radio, not accessing the medium. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 7: QoS Analysis, page 194-195
NEW QUESTION # 24
Given: The Frame Check Sequence (FCS) is a 32 CRC used for error detection.
The CRC is calculated over what?
- A. PHY Header, MAC Header and Frame Body
- B. Frame Body only
- C. Mac Header and Frame Body only
- D. PHY Header and Mac Header only
Answer: C
Explanation:
Explanation
The CRC is calculated over the MAC Header and Frame Body only. The CRC (Cyclic Redundancy Check) is a 32-bit value that is used for error detection in wireless transmissions. The CRC is calculated over the MAC Header and Frame Body of a PSDU, which are the parts of the data unit that contain information such as source and destination addresses, frame type, frame control, sequence number, payload, etc. The CRC is appended to the end of the PSDU as a FCS (Frame Check Sequence) field. The CRC is not calculated over the PHY Header or PHY Preamble, which are parts of the PPDU that contain information such as modulation, coding, data rate, etc. The PHY Header and PHY Preamble are added or removed by the PHY layer during the conversion between PSDU and PPDU. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 4: 802.11 Physical Layer, page 97-98
NEW QUESTION # 25
How is the length of an AIFS calculated?
- A. SIFS + AIFS * Time Unit
- B. SIFS * Slot Time + AIFSN
- C. AIFSN * Slot Time + SIFS
- D. DIFS + SIFS + AIFSN
Answer: C
Explanation:
Explanation
The length of an AIFS (Arbitration Interframe Space) is calculated by multiplying the AIFSN (Arbitration Interframe Space Number) by the Slot Time and adding the SIFS (Short Interframe Space). An AIFS is a variable interframe space introduced by 802.11e to help prioritize medium access for different Access Categories (ACs). An AC is a logical queue that corresponds to a QoS (Quality of Service) level for different types of traffic. Each AC has a different AIFSN value, which determines how long it has to wait before attempting to access the medium. A lower AIFSN value means a higher priority and a shorter waiting time.
The Slot Time is a fixed value that depends on the PHY type and channel width. The SIFS is the shortest interframe space that is used for high-priority transmissions, such as ACKs or CTSs. The formula for calculating the AIFS length is: AIFS = AIFSN * Slot Time + SIFS. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 7: QoS Analysis, page 194-195
NEW QUESTION # 26
You are analyzing a packet decode of a Probe Request and notice the SSID element has a length of zero. What do you conclude about the transmitting STA?
- A. The WLAN adaptor is configured in promiscuous mode
- B. The STA's WLAN adaptor is disabled
- C. The STA is operating in Ad-Hoc mode
- D. The STA is discovering a list of available BSSs
Answer: D
Explanation:
Explanation
The STA is discovering a list of available BSSs by sending a Probe Request with an empty SSID element.
This is also known as a broadcast Probe Request, as it does not specify any particular SSID to probe for. Any AP that receives this Probe Request will respond with a Probe Response containing its own SSID and other information about its BSS. This way, the STA can learn about all the BSSs in its vicinity and choose which one to associate with . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 191; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 193.
NEW QUESTION # 27
During a VHT Transmit Beamforming sounding exchange, the beamformee transmits a Compressed Beamforming frame to the beamformer. What is communicated within this Compressed Beamforming frame?
- A. Feedback Matrix
- B. Steering Matrix
- C. Beamformee Matrix
- D. Beamforming Matrix
Answer: A
Explanation:
Explanation
The beamformee transmits a Feedback Matrix within the Compressed Beamforming frame to the beamformer.
The Feedback Matrix contains information about the channel state between the beamformee and each spatial stream of the beamformer. This information is used by the beamformer to adjust its transmit weights and optimize its signal for the beamformee34. References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 11: 802.11n/ac/ax PHYsical Layer Frame Exchanges, page 4033; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 11: 802.11n/ac/ax PHYsical Layer Frame Exchanges, page 4064.
NEW QUESTION # 28
Why would a STA that supports 802.11k Radio Measurement send a Neighbor Request to an AP?
- A. To request a list of neighboring APs which the STA can use as roaming candidates
- B. To learn about neighboring interference sources and tune its RF radio accordingly
- C. To inform the current AP about the STA's intent to roam to a neighboring AP, ensuring a seamless handover
- D. To request a list of neighboring STAs which enables the STA to better pick the right protection mechanisms
Answer: A
Explanation:
Explanation
A STA that supports 802.11k Radio Measurement would send a Neighbor Request to an AP to request a list of neighboring APs which the STA can use as roaming candidates. A Neighbor Request is an Action frame that contains a subelement specifying the type of information that the STA wants to receive from the AP. A Neighbor Report is an Action frame that contains a subelement with a list of neighboring APs that match the criteria specified in the Neighbor Request. The Neighbor Report provides information such as BSSID, channel, operating class, and PHY type of each neighboring AP. This information helps the STA to perform intelligent roaming decisions based on signal quality, load, and compatibility . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 12: 802.11k/v/r/u/w/ai Amendments, page 434; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 12: 802.11k/v/r/u/w/ai Amendments, page 435.
NEW QUESTION # 29
Protocol analyzers may present field values in either binary, decimal or hexadecimal. What preceeds a hexadecimal value to indicate it is hexadecimal?
- A. 0x
- B. HEX
- C. 16x
- D. %
Answer: A
Explanation:
Explanation
A hexadecimal value is a value that uses base 16 notation, which means it can have digits from 0 to 9 and letters from A to F. A hexadecimal value is usually preceded by 0x to indicate that it is hexadecimal and not decimal or binary. For example, 0x0A is hexadecimal for 10 in decimal or 00001010 in binary. The other options are not valid prefixes for hexadecimal values.References:
CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 35
CWAP-404 Objectives, Section 2.2: Analyze field values
NEW QUESTION # 30
An RTS frame should be acknowledged by which frame?
- A. RTS-Ack
- B. Ack
- C. Block Ack
- D. CTS
Answer: D
Explanation:
Explanation
An RTS (Request to Send) frame should be acknowledged by a CTS (Clear to Send) frame. An RTS and CTS frame are types of control frames that are used to implement a virtual carrier sense mechanism called RTS/CTS. RTS/CTS is a technique that helps 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, followed by an ACK (Acknowledgement) frame from the receiver. The other options are not correct, as they are not used to acknowledge an RTS frame. An ACK frame is used to acknowledge a data frame, not an RTS frame. An RTS-Ack frame does not exist, as there is no such type of control frame in 802.11. A Block Ack (BA) frame is used to acknowledge multiple data frames in a single frame, not an RTS frame. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 6: 802.11 Frame Exchanges, page 166-167
NEW QUESTION # 31
You are performing a multiple adapter channel aggregation capture to troubleshoot a VoIP roaming problem and would like to measure the roaming time from the last VoIP packet sent on the old AP's channel to the first VoIP packet sent on the new AP's channel. Which timing column in the packet view would measure this for you?
- A. Roaming
- B. Absolute
- C. Delta
- D. Relative
Answer: C
Explanation:
Explanation
Delta is the timing column in the packet view that measures the time difference between two consecutive packets in a capture file. Delta can be used to measure the roaming time from the last VoIP packet sent on the old AP's channel to the first VoIP packet sent on the new AP's channel by selecting these two packets and looking at their delta values. The other timing columns are not suitable for this measurement because they do not show the time difference between two specific packets. Roaming is a column that shows whether a packet belongs to a roaming event or not. Relative is a column that shows the time elapsed since the beginning of the capture file. Absolute is a column that shows the date and time when a packet was captured5 References:
CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 57
CWAP-404 Objectives, Section 2.4: Analyze timing values
NEW QUESTION # 32
Which one of the following is required for Wi-Fi integration in laptop-based Spectrum Analyzer software in addition to the spectrum analysis adapter?
- A. SNMP read credentials to the WLAN controller or APs
- B. An 802.11 wireless adaptor
- C. A directional antenna
- D. A firmware upgrade for the spectrum analysis adapter
Answer: B
Explanation:
Explanation
An 802.11 wireless adaptor is required for Wi-Fi integration in laptop-based spectrum analyzer software in addition to the spectrum analysis adapter. The spectrum analysis adapter is a hardware device that captures the RF signals in the wireless environment and sends them to the spectrum analyzer software for analysis and display. The 802.11 wireless adapter is a hardware device that connects the laptop to the wireless network and allows the spectrum analyzer software to correlate the RF data with the Wi-Fi data, such as SSID, channel, and BSSID. This enables the spectrum analyzer software to provide more context and insight into the spectrum activity and its impact on the Wi-Fi network. A firmware upgrade for the spectrum analysis adapter is not required for Wi-Fi integration, but it may be needed to fix bugs or add features to the device. A directional antenna is an antenna that focuses the RF energy in a specific direction and has a high gain and a narrow beamwidth. A directional antenna can be used with a spectrum analysis adapter to pinpoint the location or source of interference or noise in the wireless environment, but it is not required for Wi-Fi integration. SNMP read credentials to the WLAN controller or APs are not required for Wi-Fi integration, but they may be useful for obtaining additional information about the wireless network configuration and performance from the network devices.References:
CWAP-404 Study Guide, Chapter 4: Spectrum Analysis and Troubleshooting, page 123 CWAP-404 Objectives, Section 4.2: Integrate Wi-Fi data with spectrum analysis data CWAP-404 Study Guide, Chapter 4: Spectrum Analysis and Troubleshooting, page 131
NEW QUESTION # 33
Where would you look in a packet trace file to identify the configured Minimum Basic Rate (MBR) of a BSS?
- A. In the Minimum Basic Rate Element in a Beacon frame
- B. In the MBR Action frame
- C. Supported Rates & Extended Supported Rates elements in a Beacon frame
- D. In the MBR Information Element in an Association Response frame
Answer: C
Explanation:
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
NEW QUESTION # 34
In the 2.4 GHZ band, what data rate are Probe Requests usually sent at from an unassociated STA?
- A. 6 Mbps
- B. The minimum basic rate
- C. MCS 0
- D. 1 Mbps
Answer: B
Explanation:
Explanation
In the 2.4 GHz band, probe requests are usually sent at the minimum basic rate from an unassociated STA. A probe request is a type of management frame that is transmitted by a STA to discover available BSSs in its vicinity. A probe request can be sent on one or more channels in either passive or active scanning mode. In passive scanning mode, a STA listens for beacon frames from APs on each channel. In active scanning mode, a STA sends probe requests on each channel and waits for probe responses from APs. A probe request is usually sent at the minimum basic rate, which is the lowest data rate among the supported rates that is required for all STAs to join and communicate with a BSS. The minimum basic rate can vary depending on the configuration of each BSS, but it is typically one of these values: 1 Mbps, 2 Mbps, 5.5 Mbps, or 11 Mbps in the 2.4 GHz band. The other options are not correct, as they do not reflect how probe requests are usually sent in the 2.4 GHz band. MCS 0 is a modulation and coding scheme used by 802.11n/ac devices in either band, but it is not a data rate per se. 6 Mbps is a data rate used by OFDM devices in either band, but it is not usually configured as a minimum basic rate in the 2.4 GHz band. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 5: 802.11 MAC Sublayer, page 123-124
NEW QUESTION # 35
Using a portable analyzer you perform a packet capture next to a client STA and you can see that the STA is associated to a BSS. You observe the STA sending packets to the AP and the AP sending packets to the STA.
Less than 2% of all packets are retransmissions. You move to capture packets by the AP and, while the retry rate is still less than 2%, you now only see unidirectional traffic from the AP to the client. How do you explain this behavior?
- A. The STA is transmitting data using more spatial streams than the potable analyzer can support
- B. There is a transmit power mismatch between the client and the AP and while the client can hear the APs traffic, the AP cannot hear the client
- C. The portable analyzer is too close to the AP causing CCI, blinding the AP to the clients packets
- D. The portable analyzer has a lower receive sensitivity than the AP and while it can't capture the packets from the client STA, the AP can receive them OK
Answer: D
Explanation:
Explanation
Receive sensitivity is the minimum signal level that a receiver can detect and decode. Different devices may have different receive sensitivity levels depending on their hardware specifications and antenna configurations.
In this scenario, the portable analyzer has a lower receive sensitivity than the AP, meaning that it requires a stronger signal to capture the packets from the client STA. The AP, on the other hand, has a higher receive sensitivity and can receive the packets from the client STA even if they have a weaker signal. This explains why the portable analyzer can only see unidirectional traffic from the AP to the client when capturing near the AP5 References:
CWAP-403 Study Guide, Chapter 4: PHY Layer Analysis, page 121
CWAP-403 Objectives, Section 4.3: Analyze PHY layer metrics
NEW QUESTION # 36
Which one of the following is an advantage of using display filters that is not an advantage of capture-time filters?
- A. Once created they are reusable for later captures
- B. They only hide the packets from view and the filtered packets can be enabled for view later
- C. They allow for focused analysis on just the packets of interest
- D. Multiple of them can be applied simultaneously
Answer: B
Explanation:
Explanation
Display filters are applied after the capture is completed and they only hide the packets from view. The filtered packets are still present in the capture file and can be enabled for view later by changing or removing the display filter. This is an advantage over capture-time filters, which discard the packets that do not match the filter criteria and cannot be recovered later34 References:
CWAP-403 Study Guide, Chapter 2: Protocol Analysis, page 37
CWAP-403 Objectives, Section 2.3: Apply display filters
NEW QUESTION # 37
ABC International has installed a new smart ZigBee controlled lighting system. However, the network team is concerned that this new system will interfere with the existing WLAN and has asked you to investigate the impact of the two systems operating simultaneously in the 2.4 GHz band. When performing Spectrum Analysis, which question could you answer by looking at the FFT plot?
- A. Is the ZigBee system using more than 50% of the available airtime?
- B. Is the ZigBee system causing an increase in WLAN retries?
- C. Do the ZigBee channels used by the lighting system overlap with the WLAN channels?
- D. Is the WLAN corrupting ZigBee system messages?
Answer: C
Explanation:
Explanation
The FFT plot is a spectrum analysis plot that shows the RF power present at a particular frequency over a short period of time. It can help identify the sources and characteristics of RF signals in the spectrum. By looking at the FFT plot, you can determine which ZigBee channels are used by the lighting system and whether they overlap with the WLAN channels in the 2.4 GHz band. ZigBee channels are 5 MHz wide and WLAN channels are 20 MHz or 40 MHz wide, so there is a possibility of overlap and interference between them. The other questions cannot be answered by looking at the FFT plot alone, as they require other types of plots or analysis tools, such as duty cycle plot, airtime utilization plot, or protocol analyzer. References: [Wireless Analysis Professional Study Guide], Chapter 3: Spectrum Analysis, page 69-70
NEW QUESTION # 38
After examining a Beacon frame decode you see the SSID Element has a length of 0. What do you conclude about this frame?
- A. SSID elements always have a length of 0
- B. The frame is corrupted
- C. This is a common attack on WISP backend SQL databases
- D. The beacon is from a BSS configured to hide the SSID
Answer: D
Explanation:
Explanation
If the SSID element has a length of 0 in a Beacon frame decode, it means that the beacon is from a BSS configured to hide the SSID. The SSID element is a part of the Beacon frame that contains the name or identifier of the BSS. The SSID element has two fields: length and value. The length field indicates how many bytes are used for the value field, which contains the actual SSID string. If the length field is 0, it means that there is no value field or SSID string in the element. This is a common technique used by some APs to hide their SSID from passive scanning clients or potential attackers. However, this technique does not provide much security, as there are other ways to discover or reveal the hidden SSID, such as active scanning or capturing probe response or association frames. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 5: 802.11 MAC Sublayer, page 122-123
NEW QUESTION # 39
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