Chapters 13 - 14 Flashcards
What is 802.11?
It is the international standard for wireless networking
What does GHz stand for?
gigahertz
What are the two main Wi-Fi frequency ranges?
2.4 GHz and 5 GHz
What normal Wi-Fi channels exist (in the USA)?
1 - 11
What is Channel 196?
It is a channel in the 5 GHz range.
What is a site survey?
You check for Wi-Fi signals that already exist.
In networking, what does sniff mean?
Sniff means listen to the network trac and try to learn from it.
What channels are commonly usable (in the USA)?
1, 6, and 11
Why are many Wi-Fi channels not used?
There is too much signal bleed between adjacent channels
What does SSID stand for?
service set identier
What is the purpose of the SSID?
It gives a name to the wireless access point.
How many characters long can an SSID be?
32
Why are some SSIDs hidden?
Hiding it provides additional security.
What Wi-Fi security methods are commonly used?
none, WEP, WPA, WPA2
What does WEP stand for?
wired equivalent privacy
What does WPA stand for?
wi-fi protected access
Which is better: WEP or WPA?
wpa
What is the legal maximum Wi-Fi signal in the USA?
100 milliwatts (mW)
What does dBm stand for?
decibels milliwatt (decibels on a milliwatt scale)
What is the dierence between dBm and dB?
dB is a relative measure. dBm is an absolute measure.
What does SNR stand for?
signal noise ratio (signal to noise ratio)
In what units is SNR measured?
decibels (dB)
How much SNR do you need for a usable connection?
20 dB
What is the typical range (in meters) for Wi-Fi signals?
100
For typical Wi-Fi, how much signal (in dB) can be used up before the
SNR is too low for useful communication?
50
For typical Wi-Fi, how much signal (in dB) is lost per meter of open air?
0.5
For typical Wi-Fi, how much signal (in dB) is lost per interior wall
(plaster-board, wooden studs)?
5
For typical Wi-Fi, how much signal (in dB) is lost per exterior wall (wood,
brick, cement block, metal studs)?
10
For typical Wi-Fi, how much signal (in dB) is lost per
oor (thick ply-
wood, support beams)?
15
What typical indoor obstacles aect Wi-Fi signal strength?
Open air, interior walls, exterior walls,
oors, furniture, cupboards, ap-
pliances, people.
What typical outdoor obstacles aect Wi-Fi signal strength?
Open air, people, trees, rain.
What con
icts happen with 802.11b networks?
microwave ovens and cordless telephones
