Troubleshooting Wireless Networks

Question 1

Bandwidth

Answer 1

Theoretical speed of data going across the network

Question 2

Throughput

Answer 2

Actual speed of data on the network

Question 3

(RSSI)

Answer 3

Received Signal Strength Indication (RSSI)
▪ Estimated measure of the power level that a radio frequency client
device is receiving from a wireless access point or wireless router

Question 4

(EIRP)

Answer 4

Effective Equivalent Isotropic Radiated Power (EIRP)
▪ Maximum power radiated from an ideal isotropic antenna, given its
antenna gain, and the transmitter power of the radio frequency system

Question 5

(dBi)

Answer 5

Decibels over isotropic (dBi)

▪ Tells signal strength being radiated from a wireless access point

Question 6

Vertical Antenna

Answer 6

Radio frequency waves extend outward in all directions away from the
antenna and the wireless access point at an equal power level

Question 7

Dipole Antenna

Answer 7

Produces radio frequency waves extending outward in two directions

Question 8

Yagi Antenna

Answer 8

A unidirectional antenna that sends the radio frequency waves in only
one direction

Question 9

Parabolic Grid Antenna

Answer 9

▪ Allows the radio waves to be transmitted in only one direction over a
longer distance than a Yagi antenna
▪ Choose a parabolic or Yagi antenna for site-to-site connections
▪ For indoor use, you are more likely to use omnidirectional and
unidirectional antennas

Question 10

Polarization

Answer 10

▪ The orientation of the electric field (or transmission) from the antenna
▪ Most Wi-Fi networks use vertical polarization

Question 11

Channel Utilization

Answer 11

▪ A statistic or measure of the amount of airtime utilization that occurs for
a particular frequency or channel
▪ Keep channel utilization under 30% to have a faster wireless network
▪ Access points and clients form a single broadcast domain when they
operate on the same channel

Question 12

(CCA)

Answer 12

Clear Channel Assessment (CCA)
▪ Listens to see if another device is actively transmitting on the channel
before attempting to send frames on that channel
▪ High channel utilization leads to slower throughput for wireless networks

Question 13

Site Survey

Answer 13

Process of planning and designing a wireless network to provide the
required wireless solution
Clients should be located in high signal strength areas to speed up the
association process

Question 14

Coverage

Answer 14

A measure of how much area around a wireless transmitter is there
sufficient signal strength for wireless devices to utilize

Question 15

Interference

Answer 15

▪ Occurs when multiple wireless networks communicate on the same
channel using the same frequency
▪ Use channels 1, 6, and 11 in the 2.4 GHz spectrum
▪ Ensure a 10-15% overlap between access points for sufficient coverage

Question 16

Attenuation

Answer 16

Reduction of signal strength between the transmission and receipt of the
signal

Question 17

Multipath Reception

Answer 17

Occurs when the transmitted signal bounces off walls and other physical
objects and then is redirected to the receiver

Question 18

Idle Timeout

Answer 18

▪ Occurs when there’s no traffic within 300 seconds
▪ Send a keep alive packet every few minutes to
remain connected

Question 19

Session timeout

Answer 19

Occurs when there’s no traffic within 1800 seconds

Question 20

Wireless network change

Answer 20

Occurs whenever the wireless local area network is

changed

Question 21

Manual deletion

Answer 21

Occurs whenever a client is removed by an

administrator

Question 22

Authentication timeout

Answer 22

Occurs when the authentication or key exchange

process fails to finish in time

Question 23

Access point radio reset

Answer 23

Occurs when a change is made to the wireless

network

Question 24

Deauthentication Attack

Answer 24

A common wireless attack used by hackers to disassociate wireless clients
and make them attempt to reconnect to the access point

Question 25

Wrong SSID

Answer 25

Service Set Identifier (SSID) is a natural language name used to identify a
wireless network in an 802.11 network

Question 26

Incorrect passphrase

Answer 26

Passphrase/ Pre-Shared Key is used to encrypt and decrypt data sent and
received by a wireless network

Question 27

Encryption mismatch

Answer 27

Occurs when the client and the access point are using different
encryption types
● WEP – RC4
● WPA – TKIP
● WPA2 – AES
▪ To fix this, attempt to reinstall the drivers for your wireless adapter
● Change protocol type
● Disable antivirus tools
● Reinstall drivers

Question 28

Captive Portal

Answer 28

A web page displayed to newly-connected Wi-Fi users before being
granted broader access to network resources

Question 29

HTTP Redirect

Answer 29

Redirects all traffic to a web server which then redirects them to a
captive portal using a 302 HTTP status code

Question 30

ICMP Redirect

Answer 30

Sends error messages and operational information indicating the success
or failure of communicating with another IP address

Question 31

DNS Redirect

Answer 31

The client is redirected by the onboard DNS server to the captive portal
webpage
-Open a web browser and try to go to any website, such as
Google.com or Facebook.com
-If that doesn’t work, determine your default gateway for the
wireless network and enter http:// and the default gateway’s IP
address, then press enter
-If that doesn’t work, then verify your DNS server IPs are not set to
something manually like 8.8.8.8, and instead allow DHCP to
autoconfigure your DNS server when connecting to the wireless
network, reattempt step 1