Question 1

Which of the following specifies when PoE technology can be used?
A)To power an antenna that is less than 200 meters away from an access point
B)To power an antenna that is more than 400 meters away from an access point
C)To power an access point that is less than 100 meters away from a wiring closet
D)To power an access point that is more than 500 meters away from a wiring closet

Accepted Answer

PoE technology can be used to power an access point that is less than 100 meters away from a wiring closet.
Key Takeaway: Power over Ethernet is used for getting DC power to an access point from a power injector. Access points located further than 100 meters from a wiring closet cannot use PoE because the DC power is sent over the same cable as the data. This is because Cat5 cables can only extend to 100 meters.

Question 2

Which of the following best defines through loss?
A)Loss of amplitude incurred between the input connector and any output connector
B)Loss of amplitude by inserting a splitter in the RF circuit
C)Loss of amplitude in the channel
D)Sum of losses incurred between the input connector and any output connector inserting a splitter in the RF circuit and channel transmission

Accepted Answer

Through loss is the loss of amplitude incurred between the input connector and any output connector.
Key Takeaway: Low insertion loss occurs by inserting the splitter in the RF circuit. Insertion loss of 0.5 dB or less is considered good for an RF splitter. A two-way splitter should have 3-4 dB loss between the input connector and either output connector. Loss higher than this can be attributed either to insertion loss or to inaccuracies in the splitter's ability to divide the power between output connectors.

Question 3

Which of the following statements is true regarding RF propagation communication?
A)The range of RF transmissions increases with frequency.
B)The range of RF transmissions in unaltered with frequency.
C)RF signals with low signal strength can be used for propagation in short ranges.
D)Due to the distances involved, sunspots do not affect RF communications.

Accepted Answer

The statement that is true regarding RF propagation communication is that RF signals with low signal strength can be used for propagation in short ranges.
Key Takeaway: RF signals with low signal strength can be used for propagation in short ranges. This is partly because of the attenuation that the signal suffers from. At low signal strengths, signal regeneration using repeaters is very expensive.

Question 4

Which of the following parameters can be used to compare the relationship between two radio waves that share the same frequency?
A)Multipath
B)Phase
C)Multiplexing
D)Velocity

Accepted Answer

Phase can be used to compare the relationship between two radio waves that share the same frequency.
Key Takeaway: The phase of a wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0. It provides information about the positioning of the two waves, with respect to their amplitude crest and troughs.

Question 5

A circuit has 2 cables with 4 dB loss each and an amplifier with a gain of 12 dB. It has one antenna with a gain of 10dBi and the attenuator has a loss of 5 dB. What is the effective gain or loss in the circuit?
A)35 dB gain
B)9 dB gain
C)9 dB loss
D)35 dB loss

Accepted Answer

The circuit has an effective gain of 9 dB.
Key Takeaway: The effective gain or loss in a circuit is additive in nature. The total loss at the cable is (-8 dB). Adding all gains and losses in the circuit ((-8 dB) + 12 dB + 10dBi + (-5 dB)) yields an effective gain of 9 dB.

Question 6

Which of the following is used to reduce the VSWR?
A)Cables with 75 ohm impedance and connectors with 50 ohms impedance
B)Cables with 50 ohms impedance and connectors with 75 ohms impedance
C)Cables and connectors with values of impedance higher than 75 ohms
D)Cables and connectors that have same value of impedance

Accepted Answer

To reduce the VSWR, you should use cables and connectors that have same value of impedance.
Key Takeaway: VSWR, or Voltage Standing Wave Ratio, is a measure of how efficiently radio-frequency power is transmitted from a power source through a transmission line into the load. VSWR can be reduced by matching the impedance of the devices used in the RF system. This means that all the devices used in the RF system must have equal values and not only 75 ohms.

Question 7

You are an RF engineer managing your company's wireless network. Which of the following is a frequency domain tool that you will use to manage the network?
A)Oscilloscope
B)Spectroscope
C)Spectrum analyzer
D)Refractivity gastro scope

Accepted Answer

Spectrum analyzer is a frequency domain tool you will use to manage the wireless network.
Key Takeaway: A spectrum or spectral analyzer is a device used to examine the spectral composition of an electrical waveform. It is also used to measure the power spectrum. A spectrum analyzer displays a power spectrum over a given frequency range. The power spectrum changes as the properties of the signal change.

Question 8

Which one of the following statement is true regarding signal attenuation?
A)A lower-frequency signal travels less than a higher-frequency signal and attenuates faster.
B)A higher-frequency signal travels less than a lower-frequency signal and attenuates faster.
C)A higher-frequency signal travels farther than a lower-frequency signal but attenuates faster.
D)A lower-frequency signal travels farther than a higher-frequency signal but attenuates faster.

Accepted Answer

The statement that is true is that a higher-frequency signal travels less than a lower-frequency signal and attenuates faster.
Key Takeaway: Because the wavelength of an electromagnetic signal is inversely proportional to the frequency, the higher the frequency, the less distance the propagated wave will travel. Additionally, a signal with a smaller wavelength and high-frequency attenuates faster.

Question 9

Which of the following IEEE standards is Wi-Fi not compatible with?
A)802.11b
B)802.11g
C)802.11n
D)802.11a

Accepted Answer

Wi-Fi is not compatible with the 802.11a standard.
Key Takeaway: Wi-Fi is a term used to identify the 802.11b wireless Ethernet standard. 802.11b uses the same unregulated radio signaling frequency at 2.4 GHz, at a maximum of 11 Mb/sec. Wi-Fi has a range of approximately 150 feet. Wi-Fi is compatible with 802.11b devices. 802.11a devices use frequencies and modulation techniques that are completely different from that used by 802.11b devices and hence, is not compatible with 802.11b.

Question 10

What is the maximum permissible output power for a FHSS system, according to the FCC rules?
A)100 mW
B)125 mW
C)200 mW
D)1 W

Accepted Answer

The maximum permissible output power for a FHSS system according to the FCC rules is 125 mW.
Key Takeaway: The older set of FCC rules defined the maximum output power at 1 watt. However, due to the significant increase in carrier bandwidth, the power limit in the newer version of the FCC rules is changed to 125 mW.

Question 11

Which one of the following is a RF phenomenon where the wave bends as it passes through a medium of different density?
A)Diffraction
B)Reflection
C)Distraction
D)Refraction

Accepted Answer

The RF phenomenon where the wave bends as it passes through a medium of different density is refraction.
Key Takeaway: Refraction describes the bending of a radio wave as it passes through a medium of different density and a constant velocity. It is similar to visible light bending as it passes from air into water. As the wave enters the dense layer of electrically charged ions, the part of the wave that enters the new medium first travels faster than the parts of the wave that have not yet entered the new medium. This abrupt increase in velocity of the upper part of the wave causes the wave to bend back toward the Earth. This bending, or change of direction, is always toward the medium that has the lower velocity of propagation.

Question 12

You want to double the distance of a signal. What is the amount in dB by which the EIRP must be increased?
A)5dB
B)6 dB
C)25 dB
D)40 dB

Accepted Answer

To double the distance of a signal, you should increase the EIRP by 6 dB.
Key Takeaway: Equivalent Isotropically Radiated Power, or EIRP, is the highest RF signal strength that is transmitted from a particular antenna. It is the actual RF power as measured in the main lobe of an antenna. It is equal to the sum of the transmit power into the antenna in dBm. As a rule of thumb, if you double or halve the distance, then you should add or subtract 6 dB to the dBi gain of the antenna respectively.

Question 13

Which of the following should you increase to improve the uptime or service level of a wireless link?
A)System operating gain
B)Link budget
C)Fade margin
D)Free space path loss

Accepted Answer

You should increase the fade margin to improve the uptime or service level of a wireless link.
Key Takeaway: Fade margin is not a property of an antenna. Fade margin is based on the link power budget. The fade margin is a figure of merit for the link, as it reflects on the reliability of the connection. To improve fade margin, you should increase TPO, use higher gain transmission or reception antenna, raise the tower height, or use a more sensitive receiver. The larger the fade margin, the less likely the link will lose its connection.

Question 14

What is the maximum percentage of Fresnel zone that should not be blocked to maintain a reliable communications link?
A)20 percent
B)40 percent
C)50 percent
D)60 percent

Accepted Answer

Fresnel zone should not be blocked more than 40 percent to maintain a reliable communications link.
Key Takeaway: Fresnel zone is the area around the visual line-of-sight that radio waves spread out into after they leave the antenna. This area must be clear to keep the signal strength. Fresnel Zone is an area of concern for 2.4 GHz wireless systems. Any more than 40 percent infringement into the Fresnel zone is likely to make a link unreliable.

Question 15

What is the ratio between the maximum peak voltage and minimum voltage on a line called?
A)Signal flux
B)EIRP
C)VSWR
D)Signal transient

Accepted Answer

The ratio between the maximum peak voltage and minimum voltage on a line is called VSWR.
Key Takeaway: Voltage standing wave ratio, or VSWR, is the difference between maximum peak voltage and minimum voltage on a line. It is represented as a ratio, for example 1.3:1. It is a measure of how efficiently radio-frequency power is transmitted from a power source through a transmission line into a load.

Question 16

You have installed a long distance point-to-point link. What is the distance beyond which earth's bulge should be considered?
A)15 miles
B)7 miles
C)20 miles
D)50 miles

Accepted Answer

The distance beyond which earth's bulge should be considered is 7 miles.
Key Takeaway: When planning for paths longer than seven miles, the curvature of the earth is a factor in path planning. It requires that the antenna be located higher off the ground. The additional antenna height needed can be calculated by the square of the distance between the antennas, divided by 8.

Question 17

Which of the following is a protocol used with the 802.11F standard as a recommended practice?
A)TPC
B)IAPP
C)CSMA/CA
D)DFS

Accepted Answer

The protocol used with the 802.11F standard as a recommended practice is IAPP.
Key Takeaway: The 802.11F recommended practice addresses vendor interoperability for AP-to-AP roaming. The Inter Access Point Protocol, or IAPP, uses announcement and handover processes that result in how APs inform other APs about roamed clients.

Question 18

Which of the following 802.11 amendments defines quality of service (QoS) at the MAC sub-layer?
A)802.11f
B)802.11d
C)802.11q
D)802.11e

Accepted Answer

The 802.11e amendment defines quality of service (QoS) at the MAC sub-layer.
Key Takeaway: 802.11e is a specification that defines QoS mechanisms for wireless devices that support bandwidth-sensitive applications, such as voice and video. 802.11e enhances the 802.11 MAC layer with a coordinated TDMA construct and adds error-correcting mechanisms for delay-sensitive applications, such as voice and video.

Question 19

What is the maximum IR allowed for the lower UNII band as defined by the IEEE?
A)40 mW
B)200 mW
C)800 mW
D)1,000 mW

Accepted Answer

The maximum IR allowed for the lower UNII band as defined by the IEEE is 40 mW.
Key Takeaway: As defined by the IEEE, the lower UNII has a maximum IR of 40 mW. The middle UNII has a maximum IR of 200 mW. The upper UNII has a maximum IR of 800 mW.

Question 20

What is the number of 312.5 KHz subcarriers that OFDM uses for transmitting data?
A)48
B)54
C)52
D)36

Accepted Answer

OFDM uses 48 312.5 KHz subcarriers for transmitting data.
Key Takeaway: OFDM is a broadband multicarrier modulation method that offers superior performance and benefits over older, more traditional single-carrier modulation methods. OFDM uses 52 subcarriers, but only 48 of them are used to transport data. The other 4 subcarriers are used as pilot carriers.

Quiz 1: Certified Wireless Network Administrator (CWNA)

Which of the following specifies when PoE technology can be used?

Which of the following best defines through loss?

Which of the following statements is true regarding RF propagation communication?

Which of the following parameters can be used to compare the relationship between two radio waves that share the same frequency?

A circuit has 2 cables with 4 dB loss each and an amplifier with a gain of 12 dB. It has one antenna with a gain of 10dBi and the attenuator has a loss of 5 dB. What is the effective gain or loss in the circuit?

Which of the following is used to reduce the VSWR?

You are an RF engineer managing your company's wireless network. Which of the following is a frequency domain tool that you will use to manage the network?

Which one of the following statement is true regarding signal attenuation?

Which of the following IEEE standards is Wi-Fi not compatible with?

What is the maximum permissible output power for a FHSS system, according to the FCC rules?

Which one of the following is a RF phenomenon where the wave bends as it passes through a medium of different density?

You want to double the distance of a signal. What is the amount in dB by which the EIRP must be increased?

Which of the following should you increase to improve the uptime or service level of a wireless link?

What is the maximum percentage of Fresnel zone that should not be blocked to maintain a reliable communications link?

What is the ratio between the maximum peak voltage and minimum voltage on a line called?

You have installed a long distance point-to-point link. What is the distance beyond which earth's bulge should be considered?

Which of the following is a protocol used with the 802.11F standard as a recommended practice?

Which of the following 802.11 amendments defines quality of service (QoS) at the MAC sub-layer?

What is the maximum IR allowed for the lower UNII band as defined by the IEEE?

What is the number of 312.5 KHz subcarriers that OFDM uses for transmitting data?