Wireless Networking

Question 1

Most common wireless standard

Answer 1

802.11 Wireless

Question 2

WAP

Answer 2

Wireless Access Point

• interconnects wireless network nodes with wired networks
• operates like a hub and works at layer 1

Question 3

link state

Answer 3

if device is connected

Question 4

IBSS

Answer 4

Independent Basic Service Set

- two or more wireless nodes communicatingin an ad hoc mode

Question 5

Infrastructure Mode

Answer 5

use one or more WAPs to connect the wireless network node centrally

Question 6

WLAN

Answer 6

Wireless Local Area Network

Question 7

BSS

Answer 7

Basic Service Set

- area serviced by a single WAP

Question 8

ESS

Answer 8

Extended Service Set

- area serviced by added WAPs

Question 9

BSSID

Answer 9

Basic Service Set Identifier

• same as MAC address for WAP
• in ad hoc, nodes generate random 48-bit string of numbers

Question 10

SSID

Answer 10

Service Set Identifier

• 32-bit indentifier inserted into the header of each frame processed by a WAP
• WAPs advertise existence by sending out continuous SSID broadcasts

Question 11

roaming

Answer 11

as clients move through different coverage areas, they will change WAP connections seamlessly

Question 12

spread-spectrum

Answer 12

broadcasts data in small, discrete chunks over the different frequencies available within a certain frequency range

Question 13

three different spread-spectrum broadcasting methods

Answer 13

DSSS - direct-sequence spread-spectrum
FHSS - frequency-hopping spread-spectrum
OFDM - orthogonal frequency-division multiplexing

Question 14

Wi-Fi Channels

Answer 14

14 channels, 20-MHz each on 2.4 GHz

40 channels with automatic channel switching on 5 GHz

Question 15

Collision detection on wired vs wireless

Answer 15

wired - CSMA/CD

wireless - CSMA/CA

Question 16

collisions on wireless

Answer 16

each sending node detects the collision and responds by generating a random timeout period for itself called a backoff

Question 17

DCF

Answer 17

Distributed Coordination Function

• method for collision avoidance on Wireless
• Defines backoffs
• requires receiving nodes send an ACK for every frame they process

Question 18

goodput

Answer 18

the acutal number of useful bits per second on a wireless network

Question 19

802.11b

Answer 19

• first standard
• 11 Mbps
• 300 ft
• 2.4 GHz
• DSSS spectrum

Question 20

802.11a

Answer 20

• 54 Mbps
• 150 ft
• 5.0 GHz
• OFDM spectrum

Question 21

802.11g

Answer 21

• 54 Mbps
• 300 ft
• 2.4 GHz
• OFDM spectrum
• backwards compatible with 802.11b
• if only g devices connected, runs in Native Mode 54 Mbps
• if b devices are connected, runs in Mixed Mode at 11 Mbps

Question 22

802.11n

Answer 22

• 100+ Mbps
• 300 ft
• 2.4 Ghz
• OFDM (QAM) spectrum quadruple-amplitude modulated
• MIMO (requires multiple antennas)
• employs tranmit beamforming (helps get rid of deadspots)
• backwards compatible with b/g
• legacy mode - sends out separate packets just for legacy devices
• mixed mode - same as legacy, but wide bandwidth
• greenfield mode - n mode only

Question 23

802.11g-ht

Answer 23

means it is connecting to a 802.11n WAP in mixed mode

Question 24

802.11ac

Answer 24

• 1 Gbps
• 3000 ft
• 5.0 GHz
• OFDM (QAM) quadruple-amplitude modulated
• MU-MIMO (multi-user)

Question 25

WPS

Answer 25

Wi-Fi Proctected Setup - push button or PIN - very susceptible to attack

Question 26

802.11i

Answer 26

security standard that enables you to set up a network with a RADIUS server and passwords encrypted with Extensible Authentication Protocol (EAP)

Question 27

RADIUS server

Answer 27

- stores usernames and passwords to store user's rights on a network

Question 28

supplicant

Answer 28

wireless client computer contacts a WAP, called a Network Access Server (NAS), requesting access to a network through a RADIUS server

Question 29

EAP

Answer 29

- developed to create a single standard to allow to devices to authenticate - not a protocol, but a PPP wrapper that EAP-compliant applications can use to accept one of many types of authentication - used in wireless networks

Question 30

EAP-PSK

Answer 30

Pre-shared Key - most popular form of wireless authentication - a shared secret code that stored on both wireless AP and client - encrypted using AES

Question 31

EAP-TLS

Answer 31

EAP with Transport Layer Security - defines use of RADIUS server as well as mutual authenticaion - requires certificates on both server and every client

Question 32

EAP-TTLS

Answer 32

Tunneled TLS - similar to EAP-TLS but only uses a single server-side certificate - very common for more secure wireless networks

Question 33

EAP-MS-CHAPv2

Answer 33

- uses a password function based on MS-CHAPv2 with the addition of an ecrypted TLS tunnel - also called Protected EAP (PEAP)

Question 34

EAP-MD5

Answer 34

- simple version of EAP that only uses MD5 hashes for transfer of authentication credentials - weak, least used version

Question 35

LEAP

Answer 35

Lightweight EAP - Cisco - combiation of MS-CHAP and RADIUS server

Question 36

EAP-FAST

Answer 36

EAP Flexible Authenticaion vioa Secure Tunneling - Cisco's replacement for LEAP - supported by all modern OSs

Question 37

802.1X

Answer 37

- Ethernet version of EAP - does not use PPP - puts EAP inside an ethernet frame - port based authenticaion - combines RADIUS-style AAA with EAP

Question 38

WEP

Answer 38

Wired Equivalent Privacy - uses a 64 or 128 bit encryption algorithm to scramble data frames - easily cracked

Question 39

WPA

Answer 39

Wi-Fi Protected Access - adpoted most of the 802.11i standard - dynamic encryption key generation - adds extra layer of secruity called TKIP (temporal key integrity protocol) - easily cracked

Question 40

CCMP

Answer 40

Counter Mode Block Chaining Message Authentication Code Protocol

Question 41

WPA2

Answer 41

Wi-Fi Protected Access 2 - fully supports 802.11i - most common is WPA2-PSK - use long passphrases to prevent hacking

Question 42

5 differences between SOHO and enterprise

Answer 42

``` robust device contruction centralized management VLAN pooling Power over Ethernet bringing personal wireless devices into the enterprise environment ```

Question 43

Wireless Controller

Answer 43

A switch designed to handle a number of WAPs simultaneously

Question 44

Difference between WAP thin and thick client

Answer 44

Thick - can access the device directly | Thin - can only be configued by a wireless controller

Question 45

LWAPP

Answer 45

Lightweight Access Point Protocol | - standard protocol used for WAP configuration

Question 46

VLAN pooling

Answer 46

randomly assign wireless clients to a VLAN

Question 47

Power over Ethernet

Answer 47

802.3af | outputs up to 25.5 watts

Question 48

site survery

Answer 48

will reveal any obstacles to creating the wireless network and will help determine the best possible location for your access points

Question 49

Wi-Fi Analyzer

Answer 49

a device that looks for and documents all existing wireless networks in the area

Question 50

High Device Density Environments

Answer 50

an area with a lot of wireless devices

Question 51

Four things needed to configure a NIC for ad hoc mode?

Answer 51

SSID IP Address Channel Sharing

Question 52

Three types of antennas

Answer 52

Omnidirectional Unidirectional Patch

Question 53

Omnidirectional Antenna

Answer 53

- radiates the signal outward in all directions | - straight wire omnidirectionals are called dipole antennas

Question 54

gain

Answer 54

- the ratio of increase from a strenghtened antenna signal - measured in dB - typical WAP is 2 dB - increasing the signal requires a bigger antenna (up to 11)