E4 Wifi 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 the channel in the 5 GHz range
What is a site survey?
You can check for WiFi signals that already exist.
In networking, what does sniff mean?
Sniff means listen to the network traffic and try to learn from it.
What channels are commonly usable (in the USA)?
1, 6, 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 identifier
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
List the four Wi-Fi security methods that 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 milliwatts) in the USA?
100
What does dBm stand for?
decibels miliwatt (decibels on a miliwatt scale)
What is the difference between dBm and dB?
dB is a relative measure, dBM is a absolute measure.
What does SNR stand for?
signal to noise ratio
In what units is SNR measured?
decibels (dB)
How much SNR (in dB) do you need for a usable connection?
20
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 ten meters of open air?
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 floor (thick plywood, support beams)?
15
What typical indoor obstacles affect Wi-Fi signal strength?
Open air, interior walls, exterior walls, floor, furniture, cupboards, appliances, people.
What typical outdoor obstacles affect Wi-Fi signal strength?
Open air, people. trees, rain.
What conflicts happen with 802.11b networks?
microwave ovens and cordless telephones
