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. References:

CWAP-404 Study Guide, Chapter 3: 802.11 MAC Layer Frame Formats and Technologies, page 101

CWAP-404 Objectives, Section 3.4: Analyze multi-user transmissions

CWAP-404 Study Guide, Chapter 3: 802.11 MAC Layer Frame Formats and Technologies, page 99

The Group Key Handshake consists of two frames excluding any Ack frames that may be required. The Group Key Handshake is used to distribute and update the Group Temporal Key (GTK) for encrypting broadcast and multicast traffic. The AP initiates the Group Key Handshake by sending a Group Key Message 1 frame to a STA, which contains the new GTK and other information. The STA responds with a Group Key Message 2 frame to the AP, which confirms the receipt of the GTK and other information. After this, both the AP and the STA can use the new GTK for encryption and decryption of broadcast and multicast traffic . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 7: 802.11 Security, page 246; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 7: 802.11 Security, page 247.

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 captured 5  References:

CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 57

CWAP-404 Objectives, Section 2.4: Analyze timing values

The 4-way handshake is the process that establishes the pairwise transient key (PTK) between the client and the AP in WPA2-PSK. The PTK is derived from the PSK, the SSID, and some random numbers exchanged in the handshake frames. The PTK is used to encrypt and decrypt the data frames between the client and the AP.  Therefore, in order to decrypt WPA2-PSK data packets, a protocol analyzer needs to capture the 4-way handshake frames and have the PSK and SSID configured in the analyzer software 1 2  References:

CWAP-404 Study Guide, Chapter 3: 802.11 MAC Layer Frame Formats and Technologies, page 87

CWAP-404 Objectives, Section 3.5: Analyze security exchanges

A VoIP phone, using WMM Power Save, requests data frames buffered at the AP by transmitting a trigger frame, which is a QoS Null frame or a QoS Data frame. WMM Power Save is a power saving mode that allows a STA (station) to conserve battery power by periodically sleeping and waking up. WMM Power Save is based on WMM (Wi-Fi Multimedia), which is a QoS (Quality of Service) enhancement that provides prioritized and differentiated access to the medium for different types of traffic. When a STA sleeps, it cannot receive any data frames from the AP, so it informs the AP of its power save status by setting a bit in its MAC header. The AP then buffers any data frames destined for the sleeping STA until it wakes up. When a STA wakes up, it sends a trigger frame to the AP, indicating its AC (Access Category), which is a logical queue that corresponds to its QoS level. A trigger frame can be either a QoS Null frame or a QoS Data frame, depending on whether it has any payload or not. The AP then responds with one or more data frames from the same AC as the trigger frame, followed by an ACK or BA (Block Acknowledgement) frame from the STA. The other options are not correct, as they are not used by a VoIP phone using WMM Power Save to request data frames buffered at the AP. A PS-Poll (Power Save Poll) frame is used by a STA using legacy power save mode, not WMM Power Save mode, to request data frames buffered at the AP. A PS-Poll frame does not indicate any AC or QoS information. Setting the More Data bit in the MAC header to 1 does not request any data frames from the AP, but indicates that there are more data frames to be sent by the STA or received by the STA. Transmitting a WMM Action frame does not request any data frames from the AP, but performs various management actions related to WMM features, such as admission control, parameter update, etc.  References:  [Wireless Analysis Professional Study Guide CWAP-404], Chapter 7: QoS Analysis, page 198-199

Real-time packet decodes are not a consideration when configuring a long-term, forensic packet capture and saving all packets to disk. Real-time packet decodes are useful for live analysis and troubleshooting, but they consume CPU and memory resources that could affect the performance of the capture process. For a long-term, forensic packet capture, it is more important to consider the analyzer location, the total capture storage space, and the individual trace file size.  These factors affect the quality and quantity of the captured packets and the ease of post-capture analysis 3 4  References:

CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 49

CWAP-404 Objectives, Section 2.1: Configure protocol analyzers

A capture visualization tool is a software application that can open a packet capture file and display various graphs, charts, tables, and statistics that illustrate the characteristics and behavior of the wireless network. A capture visualization tool can help a network administrator with little knowledge of 802.11 protocols to evaluate the overall health and performance of their wireless network by providing a visual and intuitive representation of the captured data. A spectrum analyzer is a hardware device that measures the radio frequency signals in a given frequency range and displays their amplitude, frequency, and modulation. A spectrum analyzer can help identify sources of interference and noise in the wireless environment, but it cannot open a packet capture file. Python is a programming language that can be used to write scripts or applications that manipulate or analyze packet capture files, but it requires coding skills and knowledge of 802.11 protocols. A WLAN scanner is a software application that scans for available wireless networks and displays information such as SSID, BSSID, channel, signal strength, security type, and vendor.  A WLAN scanner can help discover wireless networks and their basic parameters, but it cannot open a packet capture file 3 4 5  References:

CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 63

CWAP-404 Objectives, Section 2.5: Use capture visualization tools

CWAP-404 Study Guide, Chapter 4: Spectrum Analysis and Troubleshooting, page 117

CWAP-404 Objectives, Section 4.1: Use spectrum analysis tools

CWAP-404 Study Guide, Chapter 2: Protocol Analysis, page 33

CWAP-404 Objectives, Section 2.2: Analyze field values

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 and Extended 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

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 AP 5  References:

CWAP-403 Study Guide, Chapter 4: PHY Layer Analysis, page 121

CWAP-403 Objectives, Section 4.3: Analyze PHY layer metrics

802.11k Neighbor Requests and Neighbor Reports are sent in Action frames. An Action frame is a Management frame that is used to perform various operations or functions related to the operation or maintenance of a wireless network. An Action frame consists of a Category field that indicates the type of action being performed, and a variable-length Action Details field that contains specific information related to the action. For example, an Action frame with a Category field value of 5 indicates a Radio Measurement action, and the Action Details field may contain a Neighbor Request or a Neighbor Report subelement . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 207; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 208; CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 12: 802.11k/v/r/u/w/ai Amendments, page 434.