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 is operating in Ad-Hoc mode
-
C
The STA's WLAN adaptor is disabled
-
D
The STA is discovering a list of available BSSs
Reveal answer details
Close answer details
Correct answerD
ExplanationExplanation: 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.
An RTS frame should be acknowledged by which frame?
-
A
-
B
-
C
-
D
Reveal answer details
Close answer details
Correct answerA
ExplanationExplanation: 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
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
An 802.11 wireless adaptor
-
B
A firmware upgrade for the spectrum analysis adapter
-
C
-
D
SNMP read credentials to the WLAN controller or APs
Reveal answer details
Close answer details
Correct answerA
ExplanationExplanation: 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: 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
What is encrypted within the third message of the 4-Way Handshake?
-
A
-
B
-
C
-
D
Reveal answer details
Close answer details
Correct answerD
ExplanationExplanation: 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
Which one of the following statements is not true concerning DTIMs?
-
A
Buffered Broadcast and Multicast traffic will be transmitted following a DTIM
-
B
The DTIM interval can dictate when an STA will wake up to listen to beacon frames
-
C
DTIM stands for Delivery Traffic Indication Map
-
D
Every Beacon frame must contain a DTIM
Reveal answer details
Close answer details
Correct answerD
ExplanationExplanation: Every Beacon frame must contain a DTIM is not a true statement concerning DTIMs. DTIM stands for Delivery Traffic Indication Message, and it is a subfield within the TIM (Traffic Indication Map) element in a Beacon frame. The DTIM indicates how many Beacon frames (including the current one) will appear before the next DTIM. For example, if the DTIM interval is set to 3, it means that every third Beacon frame will contain a DTIM. Buffered broadcast and multicast traffic will be transmitted following a DTIM, so that STAs in power save mode can wake up and receive them. The DTIM interval can also dictate when an STA will wake up to listen to Beacon frames, as some STAs may choose to only listen to Beacon frames that contain a DTIM . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 200 CWAP-404 CertifiedWireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 201.
Which one of the following portions of information is communicated by bits in the PHY Header?
-
A
-
B
-
C
-
D
Reveal answer details
Close answer details
Correct answerC
ExplanationExplanation: 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
The network administrator at ABC Engineering has taken a large packet capture from one of their APs running in monitor mode. She has very little knowledge of 802.11 protocols but would like to use the capture file to evaluate the overall health and performance of their wireless network. When she asks your advice, which tool do you recommend she opens the packet capture file with?
-
A
-
B
-
C
Capture visualization tool
-
D
Reveal answer details
Close answer details
Correct answerC
ExplanationExplanation: 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 file345 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
How does a VoIP Phone, using WMM Power Save, request data frames buffered at the AP?
-
A
The VoIP phone transmits a PS-Poll frame
-
B
The VoIP phone sets the More Data bit in the MAC Header to 1
-
C
The VoIP phone transmits a WMM Action frame
-
D
The VoIP phone transmits a trigger frame, which is a QoS Null frame or a QoS Data frame
Reveal answer details
Close answer details
Correct answerD
ExplanationExplanation: 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 fordifferent 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
What does the value of the Listen Interval field in an Association Request frame indicate?
-
A
How long a STA performing active scanning will listen for Probe Responses before changing channels
-
B
How often a STA will go off channel to look for other BSSs
-
C
How often a STA in power save mode wakes up to listen to Beacon frames
-
D
How long a STA waits for an Ack before retransmitting the frame
Reveal answer details
Close answer details
Correct answerC
ExplanationExplanation: The value of the Listen Interval field in an Association Request frame indicates how often a STA in power save mode wakes up to listen to Beacon frames. The Listen Interval is expressed in units of Beacon Intervals (typically 100 TU or 102.4 ms). For example, if the Listen Interval is set to 10, it means that the STA will wake up every 10 Beacon Intervals (or about 1 second) to check for buffered frames at the AP. The Listen Interval is used by the AP to determine how long it can hold frames for a STA in power save mode before discarding them . References: CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 197 CWAP-404 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 198.
|