CWNP CWAP-404 Exam Questions Instant Access

Question 1

You're the WLAN administrator for a large retailer based at the HQ in New York. The London-based office has been complaining about WLAN disconnections around lunch time each day. You suspect this might be interference from the staff microwave, how might you test your theory from the New York office?

AAsk a local member of staff to change the frequency of the microwave and see if the disconnections stop

BAsk a local member of staff to take some pictures of the microwave, including some close-ups of the door seal so that you can assess it

CAccess the microwave remotely and run a diagnostic check

DPlace one of the London APs into spectrum analyzer mode and monitor the situation over lunch time

Answer : D

The best way to test the theory of microwave interference from the New York office is to use a remote spectrum analyzer. By placing one of the London APs into spectrum analyzer mode, you can capture and analyze the RF spectrum in the London office over lunch time. You can then look for any signs of microwave interference, such as high duty cycle, high amplitude, or frequency hopping on the 2.4 GHz band. This method does not require any physical access to the microwave or any changes to its frequency.Reference:[Wireless Analysis Professional Study Guide], Chapter 3: Spectrum Analysis, page 64

Question 2

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 ST

ALess 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?

AThe portable analyzer is too close to the AP causing CCI, blinding the AP to the clients packets

BThe STA is transmitting data using more spatial streams than the potable analyzer can support

CThere 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

DThe 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

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 AP5Reference:

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

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

Question 3

A PHY Header is added to the PSDU at which layer?

ALLC

BNetwork

CPHY

DMAC

Answer : C

A PHY header is added to the PSDU at the PHY layer. A PHY header is a part of the PPDU that contains information such as modulation, coding, and data rate. The PHY header is added by the PHY layer when it converts a PSDU to a PPDU for transmission, or removed by the PHY layer when it converts a PPDU to a PSDU for reception. The other layers do not add or remove a PHY header.Reference:[Wireless Analysis Professional Study Guide CWAP-404], Chapter 4: 802.11 Physical Layer, page 97-98

Question 4

Which one of the following is required for Wi-Fi integration in laptop-based Spectrum Analyzer software in addition to the spectrum analysis adapter?

AAn 802.11 wireless adaptor

BA firmware upgrade for the spectrum analysis adapter

CA directional antenna

DSNMP read credentials to the WLAN controller or APs

Answer : A

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. Reference:

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

Question 5

Which one of the following should be the first step when troubleshooting a WLAN issue?

AIdentify probable causes

BIdentify capture locations

CPerform an initial WLAN scan and see if any obvious issues stand out

DDefine the problem

Answer : D

The first step in any troubleshooting process is to define the problem. This involves gathering information from various sources, such as users, network administrators, network documentation, and network monitoring tools.Defining the problem helps to narrow down the scope of the issue and identify the symptoms, causes, and effects of the problem12Reference:

CWAP-403 Study Guide, Chapter 1: Troubleshooting Methodology, page 7

CWAP-403 Objectives, Section 1.1: Define the problem

Question 6

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?

ASpectrum analyzer

BPython

CCapture visualization tool

DWLAN scanner

Answer : C

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 file345Reference:

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

Question 7

You have installed a new 802.1 lac 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 are

a. 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?

AThe AP is misconfigured and needs to be reconfigured to 80 MHz operation

BNon-Wi-Fi interference is preventing the APs 80 MHz operation

CThe 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

DRRM is enabled and has dynamically picked a 20 MHz channel

Answer : B

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.Reference:[Wireless Analysis Professional Study Guide], Chapter 3: Spectrum Analysis, page 74-75

CWNP Certified Wireless Analysis Professional CWAP-404 Exam Questions