CWNP CWNA-108 Based on Real Exam Environment

The power level at the Intentional Radiator (IR) is 250 mW. The IR is the point where the RF signal leaves the transmitter and enters the antenna system. To calculate the power level at the IR, we need to consider the output power level of the transmitter, the loss of the cable, and the gain of the antenna. The formula is:

Power level at IR (dBm) = Output power level (dBm) - Cable loss (dB) + Antenna gain (dBi)

We can convert the output power level of 50 mW to dBm by using the formula:

Power level (dBm) = 10 * log10(Power level (mW))

Therefore, 50 mW = 10 * log10(50) = 16.99 dBm

We can plug in the values into the formula:

Power level at IR (dBm) = 16.99 - 3 + 16 = 29.99 dBm

We can convert the power level at IR from dBm to mW by using the inverse formula:

Power level (mW) = 10^(Power level (dBm) / 10)

Therefore, 29.99 dBm = 10^(29.99 / 10) = 999.96 mW

However, since we need to round off the answer to the nearest integer value, we get:

Power level at IR (mW) = 1000 mW

References: [CWNP Certified Wireless Network Administrator Official Study Guide: Exam CWNA-107], page 67; [CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-106], page 57.

The response that you should give to your manager’s suggestion of implementing the security practices of disabling the broadcasting of the SSID in Beacons and configuring the access points not to respond to Probe Request frames that have a null SSID field is that any 802.11 protocol analyzer can see the SSID in clear text in frames other than Beacons frames. This negates any security benefit of trying to hide the SSID in Beacons and Probe Response frames. The SSID (Service Set Identifier) is a human-readable name that identifies a WLAN and allows users to connect to it. The SSID is transmitted in clear text in several types of 802.11 frames, such as Beacon frames, Probe Request frames, Probe Response frames, Association Request frames, Association Response frames, Reassociation Request frames, and Reassociation Response frames. Some people may think that hiding the SSID can improve the security of the WLAN by making it invisible to potential intruders. However, this is not true, as hiding the SSID only removes it from Beacon frames and Probe Response frames that have a null SSID field. The SSID is still present in other types of frames that can be easily captured and analyzed by any 802.11 protocol analyzer or wireless scanner tool. Therefore, hiding the SSID does not provide any real security benefit and may even cause some compatibility and performance issues for legitimate users. References: 1, Chapter 4, page 133; 2, Section 4.1

 The data rate of a signal is the speed that the data bits in individual 802.11 data frames are sent, but it does not account for the actual amount of data that can be transmitted over time. The throughput of a connection is the flow of information over time, which is affected by various factors such as data encoding, modulation, encryption, airtime utilization, noise levels, interference, etc. Therefore, the throughput is always lower than the data rate. According to one of the web search results1, the actual throughput is normally 60-70 percent of the supported data rates. So, for a connection with a data rate of 150 Mbps, the expected throughput would be around 90-105 Mbps.

Refraction is the bending of an RF signal as it passes through a medium with a different density than free space. This can cause the signal to change its direction and speed, which can affect the accuracy and reliability of wireless communication. Refraction is influenced by factors such as temperature, humidity, and atmospheric pressure12. References: CWNA-109 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 72; CWNA-108 Study Guide, Chapter 2: Radio Frequency Fundamentals, page 67.