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CCNP ENCOR 2023 > Wireless > Flashcards

Wireless Flashcards

1
Q

What do wireless client receivers use to measure the received signal power level?

A

Received signal strength indicator (RSSI)

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2
Q

In which mode does an AP passively monitor the WLAN environment over a specifically configured channel?

A

Sniffer mode

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3
Q

Which AP mode facilitates simplified management and is ideal for environments where a large number of APs are required in a WLAN deployment?

A

Lightweight mode

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4
Q

Which type of antenna is designed to provide a 360-degree radiation pattern?

A

Omnidirectional antenna

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5
Q

When multiple wireless clients are encountering connectivity issues in the same area, where would be a good starting point for troubleshooting?

A

On the access point

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6
Q

A range of frequencies can be used for the same purpose, and such a range is often referred to as what?

A

band of frequencies

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7
Q

Channels are spaced at regular intervals, and this channel spacing is known as what?

A

Channel width or separation

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8
Q

The frequency range that is needed to transmit a signal is known as what?

A

Signal bandwidth. In WLAN communication, the signal bandwidth is defined as part of a wireless standard

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9
Q

True or False: The signal bandwidth should preferably be greater than the channel width.

A

False. The signal bandwidth should preferably be less than the channel width. This allows for different signals to be transmitted on every possible channel, with no possibility of two signals overlapping and interfering with each other.

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10
Q

A WLAN transmitter typically has a signal strength between what range?

A

0.1 W (100 mW) and 0.001 W (1 mW)

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11
Q

What term is used to describe the power gain rating of a wireless antenna?

A

dBi

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12
Q

What can be measured on a scale of 0 to 255, as defined by the 802.11 standards?

A

Received Signal Strength Indicator (RSSI)

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13
Q

What is the difference between a wireless signal that is received and the noise floor?

A

Signal-to-noise ratio (SNR). SNR is measured as positive value between 0 dB and 120 dB. The closer the value is to 120 dB, the better.

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14
Q

What is the term for wireless communication that can be multiplexed across two or more radio chains?

A

Spatial multiplexing

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15
Q

What can improve signal quality and SNR by altering the phase of the signal as it is being fed into the transmitting antenna so that the RF signal can arrive in phase at a receiver?

A

Transmit beamforming

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16
Q

What combines the multiple copies of the signal to present the best one at a particular time and thus improves SNR?

A

Maximum-ratio combining

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17
Q

What unit does the FCC use to refer to the power gain rating of a wireless antenna?

A

dBi

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18
Q

Although vendors can use a different range, what is the range used to measure RSSI as defined in the 802.11 standards?

A

0 to 255

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19
Q

If a client device receives a –70 dBm signal, and the floor noise is –90 dBm, what is the effective SNR?

A

20 dB

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20
Q

What type of chart shows how the signal spreads ahead, behind, to the right, and to the left, but not how the signal spreads up or down?

A

Azimuth chart or H-plane

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21
Q

What type of chart shows how the signal spreads ahead, behind, to the top, and to the bottom, but not how the signal spreads to the right or left?

A

Elevation chart or E-plane

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22
Q

What type of antenna radiates all around itself equally or at 360 degrees?

A

Omnidirectional antenna

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23
Q

What type of antenna radiates toward a certain direction, but the beam might be wide or narrow?

A

Directional antenna

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24
Q

What are the most basic omnidirectional antennas?

A

Dual-band dipole antennas

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25
Q

What type of antenna provides an RF pattern of thin on the vertical and horizontal planes and reaching far in a narrow beam? Also is well adapted to covering long corridors or large warehouses.

A

Yagi

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26
Q

What type of antenna is adaptable to long-range outdoor links, mainly in a point-to-point scenario?

A

parabolic dish

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27
Q

Which type of antenna adds the most gain (dBi)?

omnidirectional
directional Yagi
patch
sector

A

directional Yagi

28
Q

Which statement correctly describes the coverage area of an omnidirectional antenna?

The H-plane coverage area is larger.
The E-Plane coverage area is larger.
Both planes are covered equally.
A 360 degree spherical coverage area.

A

The H-plane coverage area is larger.

29
Q

Which statement correctly describes the coverage area of an omnidirectional antenna?

The H-plane coverage area is larger.
The E-Plane coverage area is larger.
Both planes are covered equally.
A 360 degree spherical coverage area.

A

The H-plane coverage area is larger.

30
Q

Which three antennas are examples of a directional antenna? (Choose three.)

dipole
patch
Yagi
parabolic dish
omni

A

patch

31
Q

How much dB is twice the power?

A

3 dB

32
Q

How much dB is 10x the power?

A

10 dB

33
Q

What is a measure how much energy is actually radiated from an antenna toward the main beam?

A

Effective Isotropic-Radiated Power (EIRP)

34
Q

How is EIRP calculated?

A

EIRP = Tx power (dBm) + antenna gain (dBi) – cable loss (dB)

35
Q

Which device in a split MAC architecture is responsible for 802.11 association and reassociation?

A

Wireless LAN Controller

36
Q

Which two statements correctly describe mobility groups? (Choose two.)

A mobility group can consist of up to 24 WLCs that share the context and state of client devices and WLC loading information.

The MC is responsible for caching the AP in a mobility group without being required to reauthenticate.

A wireless client can roam between any AP in a mobility group without being required to reauthenticate.

A WLC must belong to both the primary and secondary mobility groups.

Controllers in a mobility group can have different WLANs configured.

A

A mobility group can consist of up to 24 WLCs that share the context and state of client devices and WLC loading information.

A wireless client can roam between any AP in a mobility group without being required to reauthenticate.

37
Q

What are three common situations that typically cause roaming between APs to occur? (Choose three.)

Lack of switch ports available in the closet

excessive numbers of data retries

the received signal strength dropping below a threshold
hiding SSID beacons

the difference between the receive signal strength and the noise floor dropping below a threshold

client AP preference settings

A

excessive numbers of data retries

the received signal strength dropping below a threshold
hiding SSID beacons

the difference between the receive signal strength and the noise floor dropping below a threshold

38
Q

What are the two operational modes of an AP?

A

Autonomous and lightweight mode

39
Q

What is the default mode for lightweight APs?

A

Local mode

40
Q

In what AP mode does the AP maintain a tunnel back to the WLC, and client traffic is centrally switched on the WLC?

A

Local mode

41
Q

In what mode does the AP receiver acts as a dedicated sensor?

A

Monitor

42
Q

In what mode does the AP switch traffic between a VLAN and SSID if the connection back to the WLC is lost?

A

Flex Connect

43
Q

In what mode does an AP act as a dedicated bridge between two networks?

A

Bridge

44
Q

In what mode does an AP passively monitor the WLAN environment over a specifically configured channel?

A

Sniffer

45
Q

In what mode does the AP scan for MAC addresses, which it hears on the wired and wireless networks?

A

Rogue detector

46
Q

What are four ways an AP can discover a controller when booted up?

A

By using prior knowledge of the WLC
By having DHCP preprovisioned information about the WLC
By having DNS preprovisioned information about the WLC
By broadcasting on the local subnet to find the WLC

47
Q

If an AP has a list of controllers to join, what’s the order it joins them?

A

Primary controller system name

Secondary controller system name

Tertiary controller system name

Master controller (if the AP has not been previously configured with any primary, secondary, or tertiary controller names)

Load balancing across WLCs using the excess capacity value in the discovery response (if none of the above are seen)

48
Q

What is the measure of an antenna’s power?

A

Gain

49
Q

What is the shape of the transmission pattern?

A

Direction

50
Q

What is the electrical field wave’s orientation with respect to the horizon?

A

Polarization

51
Q

What is the default mode of operation for a lightweight AP?

A

Local

52
Q

What is the easiest way for a lightweight AP to discover a WLC?

A

Placing an AP on the same subnet as the WLC management interface

53
Q

True or false: An omnidirectional antenna is suitable when coverage from an antenna in all directions is required.

A

True

54
Q

What are some ways a wireless client would want to roam?

A

Low RSSI, low SNR, maximum data retry count exceeded, or proprietary load-balancing schemes

55
Q

What type of roaming occurs when the WLAN interfaces of the WLCs are on the same IP subnet?

A

Layer 2 roaming between controllers

56
Q

What type of roaming occurs when the WLAN interfaces of the WLCs are on different IP subnets?

A

Layer 3 roaming between controllers

57
Q

What is referred to as a set of WLCs identified by the same mobility group name, and it defines the realm of seamless roaming for wireless clients?

A

A mobility group

58
Q

The decision to roam from one AP to another is initiated by who?

A

Wireless client

59
Q

In terms of the time that it takes for a wireless client to roam, which of the following roaming methods is most efficient?

Layer 2 roaming
Layer 3 roaming
Intra-controller roaming
Mobility groups

A

Intra-controller roaming

60
Q

When troubleshooting a wireless connectivity issue in a particular wireless coverage area, where should you start troubleshooting when multiple users are affected?

A

AP

61
Q

Which of the following is considered to be the best first step in troubleshooting a wireless problem?

Reboot the wireless LAN controller

Gather more information to find the scope of the problem

Access the WLC and search for clients in the error logs

Access the WLC and look for alarms; if none are found, close the incident ticket

A

Gather more information to find the scope of the problem

62
Q

Which type of antenna would be a good choice if an AP’s integrated antenna does not provide enough gain to reach all the corners of a large conference room?

parabolic dish
wall-mount patch
wall-mount Yagi antenna
high-gain omnidirectional ceiling mount antenna

A

high-gain omnidirectional ceiling mount antenna

63
Q

Which two AP requirements are needed to achieve location accuracy within 5 meters (16.4 feet)? (Choose two.)

Enable FastLocate.
Use modular APs.
Increase the AP density.
Add a hyperlocation module.
Enable Fastlane.

A

Enable FastLocate
Increase the AP density

FastLocate, adds the ability to get RSSI or location information using data packets that the AP receives for higher location refresh rates. Using the data packet, location-based service updates are initiated by the network and are available more frequently, which provides more data points to accurately represent the end-user activity.

64
Q

Which controller will an AP select if there is no established controller and no master controller?

secondary
primary
tertiary
least loaded

A

least loaded

65
Q

Which tool would you use to detect and mitigate non-802.11 interference if your wireless clients are experiencing trouble connecting to APs?

Cisco CleanAir
Cisco WLC monitoring dashboard
CLI command show ap summary
Apple AirPort Utility

A

Cisco CleanAir

66
Q

When Cisco Mobility Express is deployed at branch locations, how many clients are supported by a single WLC?

Up to 100
Up to 500
Up to 50
Up to 2000

A

Up to 2000.

CCNP ENCOR 2023 (10 decks)

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