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The function of the PHY preamble is to allow the receiver to detect and synchronize with the signal. The PHY preamble is a part of the PPDU that is transmitted before the PHY header and the PSDU. The PHY preamble consists of a series of training fields that help the receiver to adjust its parameters, such as frequency, timing, and gain, to match the incoming signal. The PHY preamble also helps the receiver to estimate the channel conditions and noise level. References: [Wireless Analysis Professional Study Guide CWAP-405], Chapter 4: 802.11 Physical Layer, page 99-100

The FFT shows spectral activity in the frequency domain, while waterfall or swept spectrogram views attempt to represent RF activity over time

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-405Study Guide, Chapter 2: Protocol Analysis, page 57

CWAP-405Objectives, Section 2.4: Analyze timing values

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 analysis34 References:

CWAP-405Study Guide, Chapter 2: Protocol Analysis, page 49

CWAP-405Objectives, Section 2.1: Configure protocol analyzers

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 problem12 References:

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

CWAP-403 Objectives, Section 1.1: Define the problem