CWAP-404 Actual Questions - Instant Download 190 Questions
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CWNP CWAP-404 Exam Topics:
| Section | Objectives |
|---|---|
Protocol Analysis - 15% | |
| Capture 802.11 frames using the appropriate methods | - Select capture devices
- Install monitor mode drivers |
| Understand and apply the common capture configuration parameters available in protocol analysis tools | - Save to disk - Packet slicing - Event triggers - Buffer options - Channels and channel widths - Capture filters - Channel scanning and dwell time |
| Analyze 802.11 frame captures to discover problems and find solutions | - Use appropriate display filters to view relevant frames and packets - Use colorization to highlight important frames and packets - Configure and display columns for analysis purposes - View frame and packet decodes while understanding the information shown and applying it to the analysis process - Use multiple adapters and channel aggregation to view captures from multiple channels - Implement protocol analyzer decryption procedures - View and use a capture’s statistical information for analysis - Use expert mode for analysis - View and understand peer maps as they relate to communications analysis |
| Utilize additional tools that capture 802.11 frames for analysis and troubleshooting | - WLAN scanners and discovery tools - Protocol capture visualization and analysis tools - Centralized monitoring, alerting, and forensic tools |
| Ensure appropriate troubleshooting methods are used with all analysis types | - Define the problem - Determine the scale of the problem - Identify probable causes - Capture and analyze the data - Observe the problem - Choose appropriate remediation steps - Document the problem and resolution |
Spectrum Analysis - 10% | |
| Capture RF spectrum data and understand the common views available in spectrum analyzers | - Install, configure, and use spectrum analysis software and hardware - Capture RF spectrum data using handheld, laptop-based, and infrastructure spectrum capture solutions - Understand and use spectrum analyzer views
|
| Analyze spectrum captures to identify relevant RF information and issues | - RF noise floor in an environment - Signal-to-Noise Ratio (SNR) for a given signal - Sources of RF interference and their locations - RF channel utilization - Non-Wi-Fi transmitters and their impact on WLAN communications - Overlapping and non-overlapping adjacent channel interference - Poor performing or faulty radios |
| Analyze spectrum captures to identify various device signatures | - Identify various 802.11 PHYs
- Identify non-802.11 devices based on RF behaviors and signatures
|
| Use centralized spectrum analysis solutions | - AP-based spectrum analysis - Sensor-based spectrum analysis |
PHY Layers and Technologies - 10% | |
| Understand and describe the functions of the PHY layer and the PHY protocol data units (PPDUs) | - DSSS (Direct Sequence Spread Spectrum) - HR/DSSS (High Rate/Direct Sequence Spread Spectrum) - OFDM (Orthogonal Frequency Division Multiplexing) - ERP (Extended Rate PHY) - HT (High Throughput) - VHT (Very High Throughput) - HE (High Efficiency)
|
| Apply the understanding of PHY technologies, including PHY headers, preambles, training fields, frame aggregation, and data rates, to captured data | |
| Identify and use PHY information provided within pseudo-headers in protocol analyzers | - Pseudo-Header formats
- Key pseudo-header content
|
| Recognize the limits of protocol analyzers to capture PHY information including NULL data packets and PHY headers | |
| Use appropriate capture devices based on proper understanding of PHY types | - Supported PHYs - Supported spatial streams |
MAC Sublayer and Functions - 25% | |
| Understand frame encapsulation and frame aggregation | - Frame aggregation (A-MSDU and A-MPDU) |
| Identify and use MAC information in captured data for analysis | - Management, Control, and Data frames - MAC frame formats and contents
- 802.11 Management frame formats
- Data and QoS Data frame formats
|
| Validate BSS configuration through protocol analysis | - Country code - Minimum basic rate - Supported rates and coding schemes - Beacon interval - WMM settings - RSN settings - HT/VHT/HE operations - Channel width - Primary channel - Hidden or non-broadcast SSIDs |
| Identify and analyze CRC error frames and retransmitted frames | |
WLAN Medium Access - 10% | |
| Understand 802.11 contention algorithms in-depth and know how they impact WLANs | - Distributed Coordination Function (DCF)
- Enhanced Distributed Channel Access (EDCA)
- Wi-Fi Multimedia (WMM)
|
| Analyze QoS configuration and operations | - Verify QoS parameters in capture files - Ensure QoS is implemented end-to-end |
802.11 Frame Exchanges - 30% | |
| Capture, understand, and analyze BSS discovery and joining frame exchanges | - BSS discovery - 802.11 Authentication and Association - 802.1X/EAP exchanges - Pre-Shared Key authentication - Four-way handshake - Group key exchange - Simultaneous Authentication of Equals (SAE) - Opportunistic Wireless Encryption (OWE) - WPA2 and WPA3 - Fast secure roaming mechanisms
- Neighbor discovery (802.11k/v)
|
| Analyze roaming behavior and resolve problems related to roaming | - Sticky clients - Excessive roaming - Channel aggregation for roaming analysis |
| Analyze data frame exchanges | - Data frames and acknowledgement frames - RTS/CTS data frame exchanges - QoS Data frame exchanges - Block Acknowledgement exchanges |
NEW QUESTION # 65
What is the function of the PHY layer?
- A. Convert MSDUs to PPDUs for transmissions and PPDUs to MSDUs for receptions
- B. Convert PSDUs to PPDUs for transmissions and PPDUs to PSDUs for receptions
- C. Convert PPDUs to MSDUs for transmissions and MSDUs to PPDUs for receptions
- D. Convert PPDUs to PSDUs for transmissions and PSDUs to PPDUs for receptions
Answer: B
Explanation:
The function of the PHY layer is to convert PSDUs to PPDUs for transmissions and PPDUs to PSDUs for receptions. A PSDU (PHY Service Data Unit) is the data unit that is passed from the MAC layer to the PHY layer for transmission, or from the PHY layer to the MAC layer for reception. A PPDU (PHY Protocol Data Unit) is the data unit that is transmitted or received over the wireless medium by the PHY layer. A PPDU consists of a PSDU and a PHY header, which contains information such as modulation, coding, and data rate. The PHY layer adds or removes the PHY header to or from the PSDU during the conversion process.
NEW QUESTION # 66
You are performing 802.3 network analysis. For what are the DA and SA fields used in the frame header?
- A. They are not used; addresses are only used in the 802.11 header
- B. Defining either distance access routing or strict access routing
- C. Defining the addresses sending and receiving the frame
- D. Defining either direct access or sourced access
Answer: C
NEW QUESTION # 67
How is the length of an AIFS calculated?
- A. SIFS + AIFS * Time Unit
- B. SIFS * Slot Time + AIFSN
- C. DIFS + SIFS + AIFSN
- D. AIFSN * Slot Time + SIFS
Answer: D
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 # 68
How long, in microseconds, is the required Slot Time that is announced by an AP in an HT BSS when HR/DSSS, ERP-OFDM, and HT-OFDM client stations are associated to the AP?
- A. 20 μs
- B. 2 μs
- C. 10 μs
- D. 4 μs
- E. 9 μs
Answer: A
NEW QUESTION # 69
The IEEE 802.11 Dynamic Frequency Selection (DFS) service is capable of performing what functions? (Choose 2)
- A. Requesting and reporting of measurements in the current and other channels
- B. Using modulation switching techniques to avoid interfering with radar systems
- C. Establishing an interference baseline on all 2.4 GHz channels
- D. Suspending operations on a channel with high IEEE 802.11 co-channel interference
- E. Testing channels for radar before using a channel and while operating in a channel
Answer: A,E
NEW QUESTION # 70
What two IEEE 802.11 entities may be used to separate successful transmissions within an EDCA TXOP? (Choose 2)
- A. PIFS
- B. AIFS
- C. SIFS
- D. RIFS
- E. ACK
- F. CAP
- G. EIFS
Answer: C,D
NEW QUESTION # 71
You are repairing a misconfiguration in WMM settings on an AP.
The aCWmin and aCWmax values were all changed.
What is the default aCWmax for AC_BK?
- A. 0
- B. 1
- C. 2
- D. 3
Answer: C
NEW QUESTION # 72
Finish the statement. It is possible to distinguish between _______and ______20 MHz transmissions when looking at an FFT plot.
- A. ERP and VHT
- B. OFDM and HT
- C. HT and VHT
- D. HR/DSSS and ERP
Answer: B
Explanation:
It is possible to distinguish between OFDM 20 MHz transmissions and HT 20 MHz transmissions when looking at an FFT plot. OFDM and HT are two different modulation schemes used by
802.11 WLANs. OFDM is used by legacy 802.11a/g devices, while HT is used by newer
802.11n/ac devices. OFDM and HT have different spectral characteristics that can be observed on an FFT plot. OFDM transmissions have a flat spectrum with sharp edges, while HT transmissions have a tapered spectrum with rounded edges. This is because HT uses guard intervals and cyclic prefixes to reduce inter-symbol interference and improve performance. The other options are not correct, as they do not describe different modulation schemes or channel widths that can be distinguished on an FFT plot.
NEW QUESTION # 73
When a data frame is encrypted with WPA2, to which portion of the frame is the encryption applied?
- A. Frame body excluding the LLCPDU
- B. The whole MPDU
- C. Frame body including the LLCPDU
- D. Frame body and MAC Header
Answer: C
Explanation:
Explanation
When a data frame is encrypted with WPA2, the encryption is applied to the frame body including the LLCPDU. The LLCPDU (Logical Link Control Protocol Data Unit) is a part of the frame body that contains information such as protocol type, source and destination service access points (SAPs), and control fields. The LLCPDU is added by the LLC (Logical Link Control) sublayer to provide multiplexing and flow control functions for different upper layer protocols. When a data frame is encrypted with WPA2, which uses AES-CCMP as its encryption algorithm, both the payload and the LLCPDU are encrypted as a single unit. The MAC header and FCS are not encrypted, as they are needed for addressing and error detection purposes. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 5: 802.11 MAC Sublayer, page 115-116
NEW QUESTION # 74
Which statements are true regarding frame acknowledgement in an IEEE 802.11 WLAN? (Choose 3)
- A. In an EDCA BSS, encrypted Data frames are only acknowledged by client stations, never by access points.
- B. The RA field of ACK frames is always obtained from the Address 2 field in the corresponding frame being acknowledged.
- C. Probe request acknowledgement (sending of a Probe Response frame) is configurable in the access point and is always linked to SSID broadcast configuration in Beacons.
- D. A client station's Reassociation Request frames are only acknowledged with a Reassociation Response from the access point and not with an ACK frame.
- E. Data frame fragments are acknowledged individually (with an ACK frame).
- F. Following non-QoS Data frames with the More Fragments bit set to 1, the Duration/ID field of the ACK frame is set to a value equal to two SIFS plus the next Data fragment and its ACK.
Answer: B,E,F
NEW QUESTION # 75
Recently, three rogue APs have been connected to the network and later discovered. You want to prevent future rogue AP installations as much as possible.
What is the first step to eliminating or reducing rogue APs on the network?
- A. Define a direct policy that stipulates the ramifications of installing unauthorized devices
- B. Use IPSec between every AP and the network infrastructure
- C. Create a hash of the MAC addresses of all authorized devices and continually scan for non- matching hashes
- D. Enable rogue detection in the existing authorized APs
Answer: D
NEW QUESTION # 76
A manufacturing facility has installed a new automation system which incorporates an 802.11 wireless network. The automation system is controlled from tablet computers connected via the WLAN. However, the automation system has not gone live due to problem with the tablets connecting to the WLAN. The WLAN vendor has been onsite to perform a survey and confirmed good primary and secondary coverage across the facility. As a CWAP you are called in to perform Spectrum Analysis to identify any interference sources.
From the spectrum analysis, you did not identify any interference sources but were able to correctly identify the issue. Which of the following issues did you identify from the spectrum analysis?
- A. A high noise floor has resulted in a SNR of less than 20dB
- B. The tablets are entering power save mode and failing to wake up to receive the access points transmissions
- C. There is a power mismatch between the APs and the clients
- D. The tablets are connecting to the wrong SSID
Answer: C
Explanation:
Explanation
The most likely issue that can be identified from the spectrum analysis is a power mismatch between the APs and the clients. A power mismatch occurs when the APs transmit at a higher power level than the clients, or vice versa. This can cause asymmetric communication, where one side can hear the other, but not vice versa.
This can result in poor performance, disconnections, or packet loss. A spectrum analysis can reveal a power mismatch by showing different signal amplitudes or RSSI values for the APs and the clients on the same channel or frequency. The other options are not correct, as they cannot be identified from the spectrum analysis alone. The tablets' SSID, power save mode, and noise floor can be determined by using other tools or methods, such as protocol analysis, site survey, or device configuration. References: [Wireless Analysis Professional Study Guide CWAP-404], Chapter 3: Spectrum Analysis, page 79-80
NEW QUESTION # 77
In the 2.4 GHz band, what data rate are Probe Requests usually sent at from an unassociated STA?
- A. 1 Mbps
- B. The minimum basic rate
- C. MCS 0
- D. 6 Mbps
Answer: B
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.
NEW QUESTION # 78
What is used to respond with an uplink transmission to an MU-RTS trigger frame in the 802.11ax PHY?
- A. HE MU PPDU
- B. VHT PPDU
- C. HE TB PPDU
- D. HE SU PPDU
Answer: C
Explanation:
An HE TB PPDU (High Efficiency Trigger-Based Packet Data Unit) is used to respond with an uplink transmission to an MU-RTS trigger frame in the 802.11ax PHY (Physical Layer). An MU- RTS trigger frame is a frame that initiates a multi-user transmission opportunity (MU-TXOP) by requesting multiple stations (STAs) to send clear-to-send (CTS) frames on different spatial streams or resource units (RUs). An HE TB PPDU is a frame that contains data from multiple STAs that have been allocated RUs by an MU-RTS trigger frame or another type of trigger frame.
An HE SU PPDU (High Efficiency Single User Packet Data Unit) is a frame that contains data from a single STA using all available spatial streams or RUs. An HE MU PPDU (High Efficiency Multi User Packet Data Unit) is a frame that contains data from multiple STAs using different spatial streams or RUs without being triggered by another frame. A VHT PPDU (Very High Throughput Packet Data Unit) is a frame that uses the 802.11ac PHY and does not support multi- user transmissions.
NEW QUESTION # 79
As shown in the exhibit, a spectrum analyzer has measured both 802.11 and non-802.11 RF transmissions in the 2.4 GHz band. The exhibit shows a continuous video transmitter near channel 5.
Based upon the exhibit, what impact does the video transmitter have on WLAN operations throughout the band?
- A. The video transmitter has made no impact on WLAN operation in the band.
- B. The video transmitter is preventing all WLAN transmissions in the band.
- C. The video transmitter is preventing all WLAN transmissions on channel 6, and its impact on channels 1 and 11 is severe.
- D. The video transmitter is preventing WLAN operation on channel 6, and has only a minor impact on channels 1 and 11.
Answer: D
NEW QUESTION # 80
You are troubleshooting throughput problems for a WLAN cell. The cell is provisioned with an
802.11ac dual-band AP. Users connected with both 5 GHz and 2.4 GHz connections are reporting performance problems. The AP settings are properly optimized. No interface issues have been detected (either co- channel interference or non-Wi-Fi interference) and the number of associated users is low.
What should you analyze to resolve the issue?
- A. The 2.4 GHz radio configuration
- B. The 5 GHz radio configuration
- C. The antennas used on the client devices
- D. the Ethernet uplink and the network infrastructure
Answer: D
NEW QUESTION # 81
Protocol analyzers may present field values in either binary, decimal or hexadecimal. What precedes a hexadecimal value to indicate it is hexadecimal?
- A. %
- B. HEX
- C. 0x
- D. 16x
Answer: C
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.
NEW QUESTION # 82
Given the IEEE 802.11 Beacon frame decode shown, determine which statement is definitively true.
- A. The access point has both 1 Mbps and 2 Mbps configured as basic rates.
- B. This Beacon frame came from an ERP or HT access point.
- C. The access point is operating on channel 3.
- D. ERP mobile stations must use the RTS/CTS protocol before Data transmissions.
- E. The SSID value in this Beacon is null.
Answer: B
NEW QUESTION # 83
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