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WatchGuard > Secure Wi-Fi Essentials > Flashcards

Secure Wi-Fi Essentials Flashcards

1
Q

Radio is a transmission of _________ _______ sent to a receiver.

A

modulated signals

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2
Q

What 3 things does radio require?

A

Transmitter
Receiver
Medium

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3
Q

There are 3 bands of radio relevant to Wi-Fi, what are they?

A

2.4 GHz
5 GHz
6 GHz

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4
Q

What is the relationship between Frequency and Data Transfer.

A

The higher the Frequency the greater the Data Transfer.

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5
Q

What is the relationship between Frequency and Range.

A

The higher the Frequency the lower the Range.
Higher frequency EM Waves have a reduced ability to penetrate.

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6
Q

What is a Band?

A

A Band is a section of the radio frequency spectrum dedicated to a specific purpose.

A range of the Electromagnetic spectrum.

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7
Q

Here are some examples of devices which use the 2.4 GHz Band:

C_______ P_____
M_________
W_______ M_________ S______
B________ D______

A

Cordless Phones
Microwaves
Wireless Monitoring Systems
Bluetooth Devices

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8
Q

Here are some examples of devices which use the 5 GHz Band:
R____
R____ L_______ S______

A

Radar
Radio Location Systems

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9
Q

Here is an example of a device which uses the 6 GHz Band:
R____ S______

A

Radar Systems

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10
Q

What is Channel Width?

A

Controls how broad the signal is and how many frequencies it uses.

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11
Q

What is the relationship between Channel Width and Speed of Wireless Transmission?

A

Increasing the Channel Width increases the Speed of Wireless Transmission.

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12
Q

What can cause interference and signal degradation?
Why is that bad?

A

When the frequency range of a Channel overlaps adjacent channels.

Reduces performance.

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13
Q

What is the total Band Range of the three Radio Bands used for Wi-Fi?

A

2.4 GHz has a range of 80 MHz
5 GHz has a range of 500 MHz with DFS and 180 MHz without.
6 GHz has a range of 1300 MHz with DFS, it always uses DFS.

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14
Q

Define DFS.

A

Dynamic Frequency Selection.
Not all 5 GHz devices support DFS.
All 6 GHz devices support DFS.

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15
Q

What is the naming convention for Wi-Fi Generations?

A

Wi-Fi Gen 4 was the first officially named generation. Therefore, the previous generations are messy.

Wi-Fi Gen 6 and 6E are weird, 6E has 6 GHz Band but 6 doesn’t.

However all Generations do correlate to an IEEE Standard.

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16
Q

What is the Max Data Rate?

A

The theoretical max data transfer rate.
This is a half-duplex therefore you need to half it to get the actual max rate.

However you won’t reach that either as inefficiencies get in the way; distance, medium, walls, equipment…

Network speed always less than half Max Data Rate, usually between 15% and 30% .

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17
Q

Define MIMO Support.

A

Multiple Input Multiple Output Support.

Ability for a radio to use multiple antennas to send and receive signals.

SU-MIMO Single User, One Client
MU-MIMO Multiple Users, Many Clients

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18
Q

Antennas transmit and receive W_______ S______.
Antennas can be mounted I_________ or E_________.

A

Wireless Signals
Internally
Externally

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19
Q

There are various types of Antennas.
Name 2 of them.
What are radiation patterns?

A

Omnidirectional
Directional

The directions that signals will propagate from the antenna.

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20
Q

Describe an Omnidirectional Antenna.

A

Can transmit and receive with 360° coverage.
Most Wi-Fi access points and clients use these to provide the widest signal coverage.
The radiation pattern is Donut-like in shape.

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21
Q

Describe a Directional Antenna.

A

Directs signals in the one direction the antenna point in.
Provides a stronger signal because it’s focused in one direction, not spread out.
Typically used to extend Wi-Fi network range to difficult to reach areas.
Also used to control where a signal can be detected from, preventing signal from exiting your property for example. Security!

Typically a cone centred in the direction the antenna is pointing.

22
Q

The R____ of a wireless device greatly depends on the P____ G___ of the A______.

A

Range
Power Gain
Antenna

23
Q

What does Gain define?

A

The signal strength and range of wireless signals.
Measured in relative decibels (dB).

24
Q

What is Antenna Gain measured in?

A

Decibels relative to a reference (isotropic) antenna as a baseline.
(dBi)

25
Q

Define Beamwidth.

A

The number of degrees off-axis where the Antenna Gain drops to half its gain at the base, 0° position.

26
Q

Define Beamforming.
What advantage does it provide.
When was it added?

A

A technology that enables wireless devices with omnidirectional antennas to detect the location of other wireless devices and direct a stronger signal in the devices direction.

Provides a stronger, faster Wi-Fi signal.

Added in 802.11ac / Wi-Fi 5

27
Q

What are Spatial Streams?

A

A wireless data signal that is transmitted or received by an antenna.

The more antennas a device has, the more spatial streams it can send and receive simultaneously, which increases performance and throughput.

28
Q

How can you tell how many Spatial Streams a device has?

A

Usually listed with a colon after the antenna count, such as 4x4:3
So this device has 3 Spatial Streams.
Sometimes it isn’t stated, but rather implied to be equal to the number of antennas.

29
Q

What does a device with multiple antennas use to support multiple spatial streams?

A

MIMO
Multiple Input Multiple Output

30
Q

An 8 antenna device has 4x4 written on its’ specifications.
What does that mean?

A

4 antennas for each radio band.

31
Q

C_____ devices typically have fewer antennas A_____ P_____.

A

Client
Access Points

32
Q

SU-MIMO was added in what Wi-Fi Generation?
Explain what SU-MIMO is.

A

802.11n Wi-Fi 4

A single multi-antenna transmitter communicating with a single multi-antenna receiver.
Clients must take turns receiving transmission.

33
Q

MU-MIMO was added in what Wi-Fi Generation?
Explain what MU-MIMO is.

A

802.11ac Wi-Fi 5

Allows wireless access points to transmit and receive with multiple clients simultaneously.
Uses spatial multiplexing to direct spatial streams in the same channel to different receivers.

34
Q

Define RSSI.

A

Received Signal Strength Indicator.
This is the usual measure of signal strength, it’s the wireless signal power level received by the client device.

35
Q

What are the advantages and disadvantages of a strong signal strength?

A

More reliable connections and higher speeds.

Can cause interference with nearby wireless devices.

36
Q

Describe the Near-Far Problem

A

Access Points have stronger radio broadcast strength than Client Devices.
If the Client is far away from the Access Point, it is possible that the Access Point can broadcast to the Client; but the client isn’t strong enough to broadcast to the Access Point.

37
Q

What is a decibel(dB)?

A

A relative measure of Radio Frequency (RF) Power.
Radio Frequency Power is what is being broadcast from the antenna.

38
Q

What is a watt?

A

An absolute measure of Radio Frequency Power.

39
Q

What unit is Signal Strength represented in?
What are its’ range of values?

A

dBm
0 to -100

40
Q

What is Signal Strength?
[Measured in dBm]

A

Signal Strength is the power ratio in decibels of the measured power referenced to one milliwatt.
Relative measure of Radio Frequency Power : Absolute measure of RF Power

41
Q

Which is a better/stronger signal?
-45 dBm
-65 dBm
What are the minimum and maximum values Signal Strength?

A

-45 dBm is stronger than -65 dBm.

Minimum value is -100 dBm.
Maximum value is 0 dBm.

42
Q

What is the minimum/target Signal Strength the WatchGuard documentation stated?

A

-67 dBm

43
Q

You can increase or decrease power because of several factors, such as A______ G___ and A__________ L___ due to distance between ______ ______ and _______

A

Antenna Gain
Attenuation Loss
Access Points
Clients.

44
Q

Let X be the signal strength at your location.
You have now moved and the decibel has decreased by 3 dB.
How has X changed?
What if the decibel had increased by 3 dB?
Decreased by 10 dB?
Increased by 10 dB?

What is this relationship called?
What can you say about the relationship between signal strength and decibel?

A

X/2
2X
X/10
10X

Rule of 3’s and 10’s

Power and decibel don’t scale linearly.

45
Q

What unit is Noise Level represented in?
What are its’ range of values?

A

dBm
0 to -100

46
Q

What is Noise Level?
[Measured in dBm]

A

Indicates the amount of background noise in your environment.
If the noise level is too high, it can degrade the strength and performance of your wireless signal.

Also called noise floor.

It’s measured in the same units as Signal Strength and shares a range of 0 to -100.
The closer the value is to zero the greater the noise level, therefore lower numbers are better. Numbers of greater magnitude indicate lower background noise.

47
Q

What can be used to workout the Noise Level?

A

Spectrum Analyser

48
Q

What is the Signal-to-noise Ratio (SNR)?

A

The power difference between the signal strength and the noise level.
The greater the value the better. Lower values result in poor performance and speeds. The minimum you should have is +25 dBm.

SNR = Signal Strength - Noise Level

E.g:
Signal Strength = -41 dBm
Noise Level = -50 dBm
SNR= -41 - -50 = 9 dBm

49
Q

What tool can be used to work out noise level?

A

Spectrum Analyser

50
Q

What is a Wireless Site Survey?

A

When you analyse your physical environment and existing wireless signals.
This is accomplished using a Wireless Site Survey Utility, here are some examples:
Ekahau Site Survey
HeatMapper
AirMagnet Planner

Plays a critical role in a proper Wi-Fi deployment.

51
Q
A

WatchGuard (2 decks)

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