Wireless Fundamentals Flashcards

1
Q

Wireless LAN standards are defined in:

A

IEEE 802.11

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2
Q

What organization certifies wireless devices as 802.11 compliant, but is not directly connected with the IEEE

A

Wi-Fi Alliance

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3
Q

T/F: When a wireless device transmits a frame, all devices within range receive the frame, similar to devices connected to an ethernet hub

A

T

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4
Q

T/F: When a wireless device transmits a frame, only the target destination device receives the frame, similar to devices connected to an ethernet switch

A

F

All devices receive all frames, like an ethernet hub

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5
Q

Which of these methods is used to facilitate half-duplex connections in wireless networks?

a) CSMA/CD
b) CSMA/CA

A

b) CSMA/CA

CSMA/CD is used for wired networks

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6
Q

What does CSMA/CA stand for?

A

Carrier Sense Multiple Access with Collision Avoidance

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7
Q

Explain how CSMA/CA prevents collisions on a wireless network

A

A device will wait for other devices to stop transmitting before it transmits data itself.

If the channel isn’t free, it will wait a random period of time before sending the frame. After the wait, it will check the channel again, and send the frame if it is free.

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8
Q

What is signal absorption

A

When a wireless signal passes through a material and is converted into heat, weakening the signal

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9
Q

What is signal reflection

A

When a wireless signal bounces off a material, for example, metal. Think of elevators

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10
Q

What is signal refraction

A

When a wireless signal is bent when entering a medium where the signal travels at a different speed

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11
Q

What is signal diffraction

A

When a wireless signal encounters an obstacle and travels around it. Can result in signal blind spots

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12
Q

What is signal scattering

A

When a material causes a signal to scatter in all directions. Can result from uneven/porous surfaces, etc

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13
Q

The RF range is from _____ to _____

A

30 Hz to 300 GHz

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14
Q

What RF bands are Wireless LANs used for?

A
  • 2.4 GHz (really 2.400 GHz to 2.4835 GHz)
  • 5 GHz (really 5.150 GHz to 5.825 GHz)
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15
Q

Which wireless band provides better range in open space and better wall penetration

A

2.4 GHz

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16
Q

How many channels are there in the 2.4 GHz band?

A

11 in North America. Can vary by country

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17
Q

T/F: In larger WLANs with multiple APs, it’s important that adjacent APs don’t use overlapping channels in order to avoid interference

A

T

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18
Q

T/F: In larger WLANs with multiple APs, it’s important that adjacent APs all use the same channel in order to avoid interference

A

F

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19
Q

In the 2.4 GHz band, it is recommended to use channels ____, ____, and ____

A

Channels 1, 6, and 11

This ensures that each channel has no overlap with each other

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20
Q

T/F: The 5 GHz band consists of non-overlapping channels

A

T

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21
Q

T/F: The 5 GHz band consists of overlapping channels

A

F

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22
Q

T/F: The 2.4 GHz band consists of overlapping channels

A

T

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23
Q

T/F: The 2.4 GHz band consists of non-overlapping channels

A

F

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24
Q

A ____ AP placement pattern is recommended to avoid channel interference

A

Honeycomb

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25
Q

802.11 specifies wireless frequencies in the ___ band

A

2.4 GHz

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26
Q

802.11 wireless has a max data rate of ____

A

2 Mbps

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27
Q

802.11b specifies wireless frequencies in the ____ band

A

2.4 GHz

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28
Q

802.11b wireless has a max data rate of ___

A

11 Mbps

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29
Q

802.11a specifies wireless frequencies in the ___ band

A

5 GHz

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30
Q

802.11a wireless has a max data rate of ___

A

54 Mbps

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31
Q

802.11g specifies wireless frequencies in the ____ band

A

2.4 GHz

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32
Q

802.11g wireless has a max data rate of ____

A

54 Mbps

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33
Q

802.11n specifies wireless frequencies in the ____ band

A

2.4 GHz and 5 GHz

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34
Q

802.11n has a max data rate of ___

A

600 Mbps

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35
Q

802.11n is also known as ____

A

Wi-Fi 4

36
Q

802.11ac specifies wireless frequencies in the ____ band

A

5 GHz

37
Q

802.11ac has a max data rate of ___

A

6.93 Gbps

38
Q

802.11ac is also known as ____

A

Wi-Fi 5

39
Q

802.11ax specifies frequencies in the ____ band

A

2.4 GHz, 5 GHz, and 6 GHz

40
Q

802.11ax has a max data rate of ___

A

4 times that of 802.11ac / Wi-Fi 5

41
Q

802.11ax is also known as ____

A

Wi-Fi 6

42
Q

T/F: 802.11 devices can support one, some, or all of the 802.11 standards

A

T

43
Q

T/F: 802.11 devices can only support one of the many 802.11 standards

A

F

802.11 devices can support one, some, or all of the 802.11 standards

44
Q

What are the different service sets defined in 802.11

A
  • Independent
  • Infrastructure
  • Mesh
45
Q

All devices in a service set share the same _____

A

SSID (Service Set ID)

46
Q

What is an SSID?

A

A human-readable name which identifies the service set

47
Q

T/F: An SSID has to be unique

A

F

48
Q

T/F: An SSID doesn’t have to be unique

A

T

49
Q

What is an Ad Hoc wireless network

A

A wireless network in which two or more devices connect directly without using an AP

AKA IBSS (Independent Basic Service Set)

Ex: AirDrop, Bluetooth

50
Q

What is an IBSS wireless network

A

Independent Basic Service Set

A wireless network in which two or more devices connect directly without using an AP

AKA Ad Hoc network

51
Q

T/F: IBSS / Ad Hoc wireless networks are easily scalable to hundreds of devices

A

F

52
Q

T/F: IBSS / Ad Hoc wireless networks are not scalable beyond a few devices

A

T

53
Q

Home Wi-Fi would be classified as a what service set type?

A

Basic Service Set

54
Q

What is used to uniquely identify APs in a BSS

A

BSSID

BSSID is also the MAC address of the AP’s radio

55
Q

Wireless devices that have associated with a BSS are called ____ or _____

A

Clients or Stations

56
Q

The physical area around a BSS AP is referred to as a ____

A

BSA

Basic Service Area

57
Q

A group of devices that connect together via an access point is referred to as a ____

A

BSS

Basic Service Set

58
Q

A BSS is what type of service set?

A

Infrastructure

59
Q

An ESS is what type of service set?

A

Infrastructure

60
Q

To create larger wireless LANs beyond the range of a single AP, what service set is used?

A

ESS

Extended Service Set

61
Q

T/F: In an ESS, each AP with their own BSS is connected via wired network

A

T

62
Q

T/F: In an ESS, each AP with their own BSS is connected via other APs

A

F

That would be an MBSS

63
Q

In an ESS, each BSS uses the same ___

A

SSID

64
Q

In an ESS, each BSS has a unique ____

A

BSSID

65
Q

In an ESS, how does each BSS avoid interference

A

By using different channels

66
Q

What is wireless roaming?

A

When a client passes between APs without having to reconnect, providing a seamless Wi-Fi experience when moving between BSAs

67
Q

When a client passes between APs without having to reconnect, this is referred to as:

A

Roaming

68
Q

In an ESS, each BSA should overlap by:

A

10-15%

69
Q

In situations where it would be difficult to run an Ethernet connection to each AP, what can be used?

A

MBSS

Mesh Basic Service Set

70
Q

How do mesh APs provide back haul to other network infrastructure

A

Two radios are used, one for providing a BSS to clients, and one to form a back haul network with other APs

71
Q

In an MBSS, the AP that is directly connected to the wired network is referred to as:

A

RAP

Root Access Point

72
Q

In an MBSS, the APs that aren’t directly connected to the wired network are referred to as:

A

MAPs

Mesh Access Points

73
Q

In 802.11, the upstream wired network is called the _____

A

DS

Distribution System

74
Q

T/F: Each wireless BSS or ESS is mapped to a VLAN in the wired network

A

T

75
Q

T/F: Each WLAN uses a unique BSSID, usually by incrementing the last digit of the BSSID by one

A

T

76
Q

T/F: Each WLAN uses the same BSSID, and VLAN seperation is accomplished by MAC address mapping

A

F

77
Q

Describe what an AP in repeater mode does

A

Re-transmits any signal received from another AP. Repeaters really need at least 2 radios to function properly

78
Q

Describe what an AP in workgroup bridge mode does

A

Operates as a wireless client of another AP, and can be used to connect wired devices to the wireless network

79
Q

Describe what an AP in outdoor bridge mode does

A

Connects networks over long distances without a physical cable connecting them. Ubiquiti AirFiber is an example.

80
Q

When using the 2.4 GHz band, which channels should be selected when using multiple APs?

a) 2, 6, 10
b) 1, 6, 11
c) 11, 12, 13
d) 2.4 GHz channels do not overlap, so any channels can be used

A

b) 1, 6, 11

81
Q

If an enterprise’s network is mostly wires, what is the purpose of an AP in the network?

a) To connect wireless devices to the wired network
b) To centrally manage all wireless devices
c) To provide additional security for wireless clients
d) To create additional VLANs in the network

A

a) To connect wireless devices to the wired network

82
Q

Which of the following bands are commonly used by wireless LANs (pick 2)?

a) 2.4 GHz
b) 2.5 GHz
c) 4.5 GHz
d) 5 GHz

A

a) 2.4 GHz
d) 5 GHz

83
Q

Which of the following statements about an ESS are true (pick 2)

a) Each BSS uses a unique SSID
b) Each BSS uses a unique BSSID
c) Roaming can provide seamless connectivity when moving between APs
d) Each BSS uses the same channel

A

b) Each BSS uses a unique BSSID
c) Roaming can provide seamless connectivity when moving between APs

84
Q

Which of the following statements is not true about an AP that provides multiple BSSs

a) Each BSS can use a unique SSID
b) Each BSS shares the same BSSID
c) Each BSS is mapped to a separate VLAN on the wired network
d) The AP should connect to the switch via a trunk

A

b) Each BSS shares the same BSSID

85
Q

You admin the network of a factory. You want to install three 802.11b APs in the admin offices. Which channels should you configure on the three APs?

a) Any channel, as long as each AP uses a different channel
b) 1, 2, and 3
c) Any channel, as long as all three APs use the same channel
d) 1, 7, and 13
e) 1, 6, 11

A

e) 1, 6, and 11