Chapter 1

Question 1

Which WLAN organization standardizes how data is transmitted over the frequencies defined by the FCC?

Answer 1

IEEE (Institute of Electronic and Electrical Engineers)

Question 2

Which 802.11 standards are used by 2.4GHz? 5GHz?

Answer 2

2.4GHz (802.11, b, g, n).

5GHz (802.11a, n, ac)

Question 3

What does ISM stand for? U-NII?

Answer 3

2.4GHz Industrial, Scientific, Medical.

5GHz Unlicensed-National Information Infrastructure

Question 4

Which channels are known as U-NII 2E?

Answer 4

Channels 100-144

Question 5

What is it called when two nearby APs use overlapping channels?

Answer 5

Co-channel interference

Question 6

Which standard introduced channel bonding? What does it do?

Answer 6

The 802.11n standard introduced channel bonding. Channel bonding uses the frequency ranges of two channels and treats them as a single, wider channel.

Question 7

What is the difference between Wave 1 and Wave 2 APs?

Answer 7

Wave 1 uses 3 spatial streams and can bond up to 4 channels for 80MHz-wide channels. Wave 2 uses up to 4 spatial streams and can bond 8 channels for 160MHz-wide channels. Also introduces MU-MIMO.

Question 8

What speed is considered VHT?

Answer 8

Speeds upwards of 150Mbps are considered VHT. 802.11n added the term HT.

Question 9

What two features allow WLAN systems to operate in the radar spectrum?

Answer 9

802.11h features Dynamic Frequency Selection and Transmit Power control.

Question 10

What is the standard that provides QoS?

Answer 10

802.11e is used for QoS

Question 11

Name the priorities for traffic from highest to lowest

Answer 11

Voice, video, best-effort and scavenger

Question 12

What traffic does WMM prioritize?

Answer 12

Wireless Multimedia prioritizes voice and video

Question 13

Which security standard is implemented by WPAv2?

Answer 13

802.11i

Question 14

What 3 features are supported by 802.11i?

Answer 14

Authentication, encryption and hashing. Hashing detects if an attacker captures a packet, modifies the data, and then resends it. (Man-in-the-middle attack)

Question 15

What is 802.11k?

Answer 15

Radio measurement standard. It improves a client’s search for nearby APs by creating an optimized list of channels that it picks an AP from when the signal strength of the current AP weakens.

Question 16

What is 802.11v?

Answer 16

Improved transition between access points using a technique called Basic Service Set transition-management.

Question 17

What types of frames are used to establish, control and maintain client connections?

Answer 17

Management frames

Question 18

What type of frames use RTS/CTS and ACK frames to access the channel and acknowledge receipt of frames?

Answer 18

Control frames

Question 19

What levels are considered a typical noise floor?

Answer 19

Between -90 dBm and -100 dBm

Question 20

What is a duty cycle?

Answer 20

How often an interferer is active over a given time period

Question 21

What is the horizontal plane?

Answer 21

The azimuth is an overhead view as if you were hovering over the AP. Also known as the H-plane.

Question 22

What is the vertical plane?

Answer 22

The elevation plane shows a vertical, side view. Also known as the E-plane

Question 23

True or false? Antennas do not draw power from the AP so they do not “add power” to the signal.

Answer 23

True.

Question 24

What unit is used to measure the gain of an antenna?

Answer 24

dBi

Question 25

Where is an AP’s RF power specified at?

Answer 25

At its antenna connector.

Question 26

What dBm is equal to 100mW?

Answer 26

20 dBm is equal to 100mW.

Question 27

0dBm is equal to how many mW?

Answer 27

0dBm = 1mW

Question 28

What is the formula for EIRP?

Answer 28

Tx Power - cable loss + antenna gain = EIRP = The total RF output power of an AP.

Question 29

What is the difference between BSS and ESS?

Answer 29

The BSS is the AP WLAN and all associated clients in that AP’s coverage area. The ESS is that but configured across multiple APs.

Question 30

What is a major differentiator between Aruba and other vendor’s WLANs?

Answer 30

A user’s access to resources can be different through Role Based Access Control (RBAC) and Firewall policies.

Question 31

What SNR level is considered low?

Answer 31

Low SNR is defined as being 30 dBm or lower. This means if a client’s signal strength is -70 dB and the noise floor was -100 dB, you’d have an SNR of 30 dBm.