The DHCP server should be configured to provide the IP address information to the APs, but it may also be required to pass information for option 43. Option 43 is a vendor information option and can be used for any vendor purpose. The vendor class identifier (VCI) (for example, “Cisco AP c3600”) is used with option 60 to determine the appropriate information to return with option 43.

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- 405 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 197; CWAP- 405 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 6: MAC Sublayer Frame Exchanges, page 198.

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.  References:  [Wireless Analysis Professional Study Guide CWAP- 405 ], Chapter 3: Spectrum Analysis, page 70-71

 When performing protocol analysis, you would look at the HT Information Element in the Beacon frame to determine which one of the four HT protection modes the AP is operating in. The HT Information Element contains various subfields that provide information about the HT network configuration and operation. One of these subfields is the HT Protection field, which indicates whether any protection mechanisms are required for mixed-mode operation with non-HT STAs. The four possible values for this field are:

No Protection: No protection mechanisms are required.

Non-member Protection: RTS/CTS or CTS-to-self protection is required for all HT transmissions.

20 MHz Protection: RTS/CTS or CTS-to-self protection is required for all HT transmissions using a 40 MHz channel.

Non-HT Mixed Mode: All HT transmissions must use a non-HT preamble and header . References: CWAP-405 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 11: 802.11n/ac/ax PHYsical Layer Frame Exchanges, page 378; CWAP-405 Certified Wireless Analysis Professional Study and Reference Guide, Chapter 11: 802.11n/ac/ax PHYsical Layer Frame Exchanges, page 379.

Open Authentication without encryption is not allowed when operating a BSS in the 6 GHz band, according to the 802.11 standard. Open Authentication is a type of authentication method that does not require any credentials or security information from a STA (station) to join a BSS (Basic Service Set). Open Authentication can be used with or without encryption, depending on the configuration of the BSS and the STA. Encryption is a technique that scrambles the data frames using an algorithm and a key to prevent unauthorized access or eavesdropping. However, in the 6 GHz band, which is a newly available frequency band for WLANs, Open Authentication without encryption is prohibited by the 802.11 standard, as it poses security and interference risks for other users and services in the band. The 6 GHz band requires all WLANs to use WPA3-Personal or WPA3-Enterprise encryption methods, which are more secure and robust than previous encryption methods such as WPA2 or WEP. The other options are not correct, as they do not describe scenarios where Open Authentication without encryption is not allowed by the 802.11 standard. When operating a BSS in the CBRS band, which is another newly available frequency band for WLANs, Open Authentication without encryption is allowed, but not recommended, as it also poses security and interference risks for other users and services in the band. When operating a BSS in FIPS mode, which is a mode that complies with the Federal Information Processing Standards for cryptographic security, Open Authentication without encryption is allowed, but not compliant, as it does not meet the FIPS requirements for encryption algorithms and keys. When operating a BSS in a government facility, Open Authentication without encryption is allowed, but not advisable, as it may violate the government policies or regulations for wireless security.  References:  [Wireless Analysis Professional Study Guide CWAP- 405 ], Chapter 8: Security Analysis, page 220-221

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.  References:  [Wireless Analysis Professional Study Guide], Chapter 3: Spectrum Analysis, page 64