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Tentor > Trådlösa Nätverk > Flashcards

Trådlösa Nätverk Flashcards

1
Q

802.11 operates on which OSI model layers?

A

Layer 1 & 2

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2
Q

Which term is used generally to describe an 802.11 radio capable unit?

A

Station

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3
Q

How can you represent an increase in power that is about equal to double the original value by using dB?

A

+3 dB represents an approximate power change equal to twice the original power value.

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4
Q

How fast does electromagnetic waves travel?

A

They travel at the speed of light

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5
Q

Visible light is a type of?

A

Electromagnetic wave

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6
Q

Does electromagnetic waves need a medium to propagate?

A

No

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7
Q

Which propagation phenomena describes how a signal can bend or change direction as a result of passing through a medium of a different density?

A

Refraction

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8
Q

Wi-Fi Alliance recently introduced a new naming scheme. Which name is used by the Wi-Fi Alliance to refer to 802.11ac technology?

A

Wi-Fi 5

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9
Q

What is the frequency bandwidth for a single channel 802.11b DSSS transmission?

A

The frequency bandwidth for a single channel 802.11b is 22 MHz wide.

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10
Q

Which technique divides a single 802.11 channel into 64 subcarriers, of which 52 are data subcarriers, that are then transmitted in parallel with each other?

A

OFDM

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11
Q

How many non-overlapping channels are there in the 2.4GHz ISM band?

A

3 channels

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12
Q

Which are the non-overlapping channels in the 2.4GHz band that you should use in your channel reuse plan in most parts of the world?

A

Channel 1, 6 & 11

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13
Q

Are all 5GHz channels are considered non-overlapping

A

Yes

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14
Q

In some 5GHz U-NII bands DFS is a requirement. What is the purpose of DFS?

A

DFS is a radar avoidance technique

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15
Q

Which Wi-Fi certification program certifies functionality in the 6GHz frequency band?

A

Wi-Fi 6E

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16
Q

What is the most common distribution system medium (DSM) for a WLAN implementation?

A

Ethernet

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17
Q

In general, how does the gain of an antenna affect the vertical beamwidth of an omnidirectional antenna?

A

If the gain is increased, the vertical beamwidth gets more narrow

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18
Q

Statement:
Antenna polarization describes how the amplitude of the transmitted signal is oscillating from the antenna, for example horizontal or vertical polarization.

A

True

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19
Q

What kind of an antenna is a Yagi antenna classified as?

A

A directional antenna

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20
Q

What kind of an antenna is a Dipole antenna classified as?

A

An omnidirectional antenna

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21
Q

Which protocol is used to connect a LAP and WLC?

A

CAPWAP

22
Q

What needs to be true for a LAP and WLC to connect?

A

The LAP and WLC must have IP-connectivity to each other

The LAP needs to discover a controller IP-address before it can join

23
Q

What medium access strategy is used in 802.11 to share the medium?

A

CSMA collision avoidance

24
Q

What’s the purpose of Interframe space period?

A

The interframe space period allows certain frames to be prioritized, such as ACK-frames

25
Q

What is the purpose of a Block ACK frame?

A

A block ACK frame can acknowledge multiple frames at once

26
Q

What technique can be implemented to prevent management frames from being spoofed?

A

Management frame protection (MFP)

27
Q

What’s the supplicant in 802.1x ?

A

The supplicant is the host that requests authentication

28
Q

Besides the supplicant, which other roles are defined in 802.1x?

A

Authenticator & authentication server

29
Q

Roaming is initiated by which station?

A

The client station

30
Q

Roaming is usually based on parameters such as…?

A

RSSI, noise level and error rate

31
Q

What allows encrypted data frames in an open network?

A

WPA3 OPE

32
Q

Whats the purpose of an Offline dictionary attack?

A

The purpose is to acquire a users password

33
Q

What type of system can be deployed to monitor and protect the wireless network from attacks and threats?

A

A WIPS server

34
Q

What’s the traditional way to determine AP-placements during a site survey, where a physical AP is tested and evaluated at different locations?

A

AP-on-a-stick

35
Q

What describes the purpose of attenuation spot checking in the hybrid site survey?

A

Determine attenuation values of different materials to be used in the predictive design

36
Q

Which technique allows a station to adjust the data rates used for transmission dynamically based on received signal quality?

A

DRS, Dynamic rate shifting

37
Q

What does this describe?

Two clients connected to the same BSS can hear the AP, but cannot hear each other

A

A hidden node problem

38
Q

What’s the purpose of capacity design when implementing a new network?

A

Capacity design ensures that we have enough radio capacity to provide for the users and their applications

39
Q

What is the purpose of TPC in Cisco RRM?

A

TPC adjusts the transmit power of APs to reduce interference

40
Q

What does this describe?

A single radio equipped with multiple antennas could choose which one to use

A

pre-802.11n antenna diversity

41
Q

A user is upgrading from an old 802.11n smartphone without MIMO support, to a newer 802.11n 2x2:2 MIMO smartphone.

In his apartment he has a 4x4:4 802.11n certified router.

What can the user expect in regards to data rates used with his new device compared to the data rates he used to achieve?

A

The data rate will be doubled

42
Q

What’s the maximum data rate that you can achieve with the protocol 802.11ax

A

9.687 Gbps

43
Q

What’s the maximum data rate that you can achieve with the protocol 802.11g

A

54 Mbps

44
Q

What’s the maximum data rate that you can achieve with the protocol 802.11b

A

11 Mbps

45
Q

What’s the maximum data rate that you can achieve with the protocol 802.11n

A

600 Mbps

46
Q

What’s the maximum data rate that you can achieve with the protocol 802.11ac

A

6.933 Gbps

47
Q

Which protocol is the only protocol that does not use OFDM?

A

802.11b

48
Q

What spread spectrum technique does the 802.11b protocol in question use?

A

DSSS

49
Q

There are four 802.11 protocols that can be used for communication in the 2.4GHz band, which are they?

A

802.11b, 802.11n, 802.11g, 802.11ax

50
Q

Legacy 802.11 shared key authentication used static encryption keys. With 802.11i and WPA2 authentication dynamic encryption keys are used instead.

Explain the main difference between static encryption keys and dynamic encryption keys. How does dynamic encryption keys help protect a users data?

A

The main difference between the static and dynamic encryption key is that for static, every device has the same key, meaning that if a malicious actor figures out the key, the whole communication can be decrypted.

Dynamic encryption keys protects the users by randomizing out an encryption key to every user and session. This hardens the possibility of eaves dropping on the transmissions.

51
Q
A

Tentor (4 decks)

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