Volume 2 - Chapter 1: Fundamentals of Wireless Networks

Question 1

What transmission duplex is used for 802.11 wireless communications?

Answer 1

Half Duplex

Wireless clients share airtime with each other. As such, only half duplex communications are allowed within the 802.11 standard to avoid collisions.

Question 2

A group of wireless clients connected to a shared AP forms a ___.

Answer 2

Basic Service Set (BSS)

Question 3

Describe the what it means for an AP to operate in “Infrastructure Mode”.

Answer 3

The access points offers all necessary services to form the infrastrucutre of a wireless network.

Question 4

The AP and members of the BSS all must use the same ____ to communicate properly

Answer 4

Channel.

Question 5

The area of range that an access point can provide a usable signal to is referred to as?

Answer 5

The Basic Service Area (BSA).

Question 6

Describe the purpose of the beacon frame which is sent by an access point.

Answer 6

The beacon frame is used for the AP to advertise the existance of the BSS so clients can be made aware of its existance.

Question 7

What piece of information is contained within the beacon frame that identifies the BSS?

Answer 7

The Service Set Identifier (SSID)

Question 8

What piece of information identifies the access point’s own unique radio MAC address?

Answer 8

The Basic Service Set Identifier (BSSID)

Question 9

What different ways can wireless devices learn about Basic Service Sets in their range?

Answer 9

By performing passive scanning; waiting and listening for beacons advertised by an AP.

Or by sending 802.11 probe requests; actively trying to receive information about nearby BSSs

Question 10

An 802.11 client of a BSS is also referred to as a?

Answer 10

Station (STA)

Question 11

Describe the function of the Ethernet Distribution System (DS).

Answer 11

The DS is the back haul wired ethernet network that provides the backend network connectivity to the AP.

Question 12

What layer of operation is taking place when an 802.11 wireless network is bridged to an 802.3 wired ethernet network?

Answer 12

Layer 2, for example:

The SSID “MyNetwork” is mapped to VLAN 10 on the switch

Question 13

Why does an AP have multiple BSSIDs?

Answer 13

To uniquely identify each SSID that it is broadcasting. Wireless clients connected to different SSIDs communicate with the AP through different BSSIDs.

Question 14

A wireless network that is formed by multiple access points in different locations, but still connected to the same distribution system is referred to as?

Answer 14

A Extended Service Set (ESS).

Question 15

Describe the function of the Extended Service Set Identifier (ESSID).

Answer 15

The ESSID uniquely identifies an ESS that exists across multiple APs

Question 16

What term describes the following?

A small wireless network that exists to allow wireless clients to directly communicate with each other

Answer 16

A Independant Basic Service Set (IBSS)

Also refered to as an Ad Hoc wireless network.

Question 17

A device that takes the signal it receives and repeats or retransmits it in a new cell area is refered to as?

Answer 17

A repeater.

Question 18

Describe the purpose of a Workgroup Bridge (WGB).

Answer 18

To provide wireless capabilities to a device that normally only supports wired communications.

Question 19

Derscribe the purpose of an outdoor bridge?

Answer 19

To provide a point-to-point wireless network between buildings or cities so their LANs can communicate.

Question 20

What type of bridge is required to connect multiple buildings to a central-shared site?

Answer 20

A point-to-multipoint bridge.

Question 21

Which 2.4 GHz channels are considered non-overlapping?

Answer 21

1, 6, and 11

Question 22

Which 5 GHz channels are considered non-overlapping?

Answer 22

Technically all of them, each usable channel inceases by 4 to ensure there is no overlap

For example: 36, 40, 44, and 48

Question 23

What is the wireless band and max data range used by the original wireless standard?

Answer 23

802.11-1997

Only uses a 2.4 GHz band
2 Mbps max

Question 24

What is the year, wireless band, and max data range used by the 802.11b standard?

Answer 24

Released in 1999
Only uses a 2.4 GHz band
11 Mbps max

Question 25

What is the year, wireless band, and max data range used by the 802.11g standard?

Answer 25

Released in 2003
Only uses a 2.4 GHz band
54 Mbps max

Question 26

What is the year, wireless band, and max data range used by the 802.11a standard?

Answer 26

Released in 1999
Only uses a 5 GHz band
54 Mbps max

Question 27

What is the year, wireless band, and max data range used by the 802.11n standard?

Answer 27

Released in 2009
Uses a 2.4 & 5 GHz band
600 Mbps max

Question 28

What is the year, wireless band, and max data range used by the 802.11ac standard?

Answer 28

Released in 2013
Only uses a 5 GHz band
6.93 Gbps max

Question 29

What is the year, wireless band, and max data range used by the 802.11ax standard?

Answer 29

Released in 2021
Uses 2.4, 5, and 6 GHz bands
27.72 Gbps max