A+ 1001: wireless Flashcards
IEEE 802.11
Primary standard for wireless communication
Two modes:
- infrastructure mode
- adhoc mode
Based on ISM ( Unlicenced industrial, scientific, and medical radios bands)
- 2.4 GHz and 5 GHz band
WAP
Wireless Access Point
Bridges 802.11 and ethernet networks
Infrastructure mode
uses a wap and network card connection
Wireless Network Card
Manages Network activity on a device
connects to a SSID that is configured on a WAP
Where is the antenna for the wireless card in laptops and mobile devices
Usually, it is inside the monitor itself
For phones and tabs it is in the case itself
SSID
Service Set Identifier
WAPs are configured with SSID
The network/connection name that appears on devices when look for a connection
Adhoc mode
no WAP, only network cards connecting to one another
Used to connect computer together wirelessly
Antenna
3 Types
- Omni-directional: Radiates signal in all directions like a ball
- Dipole: Two omnidirectional antennas pointing in opposite direction: Radiates signal in a big flat donut like circle
- Patch: Looks flat. Radiates signal as the half-a ball
- Yagi: Highly directional. The radiation pattern looks like a football. Good for sending signals long distances
- Parabolic: Looks like a dish. Used for long-distance throws
802.11 extensions
- 11a : 54 Mbps 5Ghsz (wifi 1)
- 11b : 11 Mbps 2.4Ghsz (wifi 2)
- 11g: 54 Mbps 2.4Ghsz (wifi 3)
- 11n: 100Mbps 2.4/5Ghsz (MIMO) (wifi 4)
- 11ac (multi-user MIMO) (wifi 5)
b and g are backward compatible
What is a band?
A range of radio frequencies.
2.4 GHZ band range and channels
2.412 - 2.4884 Ghz
Japan 14 channels
Europe: 13 channels
US: 11 channels
5 GHz Band range and channels
5.150 - 5.875 GHz
Channels: (no odd numbers)
36, 40, 44,48,52,58,60,64
MIMO
multiple in/ multiple out
Allows a WAP to use multiple antennas to change it’s radiation signal pattern to zero in on a device
MIMO requires 802.11n
MU-MIMO can zoom in on multiple users at a time.
MU-MIMO requries 802.11ac
What should you do before plugging in a WAP or Router
Do an area survey to see wireless connections already in the same area and to see how congested the channels are
This is important when setting up 2.4 GHz channels as these are usually set manually
The 5GHz channels will configure itself
Maximum broadcast power that ISM allows
1 watt
Sight Survey
shows available channels in an ISM band
What happens when we click on “remember this
What happens when we click on “automatically connect to this network”
It creates a profile
profiles can be accessed in Settings > Netowrk & Internet > wifi > Mange known networks,
Troubleshooting: Cannot connect to wifi network that you’ve connected to in the past
- Remove the profile by right-clicking on network and selecting “forget”
- Login again
Troubleshooting: cannot connect to an SSID
- NIC is configured as DHCP client (APIPA)
- Passwords have changed
- SSID has changed
- Low RF Signal (turns on and off)
- NIC has static IP
WMN
Wireless Mesh network
one base station, with SSID that connects to the network
With other stations (beacons/satelite) that connects to base station
Often used in small office or home offices
Has it’s own encryption
RFID
Radio Frequency Identification
RFID tags are little radios that are activated and energised by reader
NFC
Near Field Communication
It’s RFID
Used for Tap to Pay, or Tap to Print
Bluetooth
Connects two devices together in a PAN (personal area network)
3 Classes
- 100mW 100M
- 2.5 mW 10m
3 1 mW 1m
Troubleshoot: Low RF Signal
- Too far from access point. Move closer to the router
- Antennas are not set up properly. Move antennas
- The access point’s signal is weak, boost Signal Strength
- SSID is not broadcasting (need to configure a profile)
Troubleshoot: Limited Connectivity
Slow transfer speeds
- Radio signal interference (microwaves, radios etc), -> Remove interference
- Low RF signal
Trouble Shooting: Intermittent connectivity
Connection interruptions
- Low RF signals, Modern routers will often restart
- Too many connections on network (increase the amount of waps, or configure QOS)
Which is not a Wi-Fi capable device?
a. ) WAP
b. ) Switch
c. ) Smartphone
d. ) Tablet
b.) Switch
A switch is a hard-wired network device. WAPs, smartphones, and tablets are all Wi-Fi capable.
Which 802.11 standard runs on 5GHz
a. ) 802.11a
b. ) 802.11b
c. ) 802.11c
d. ) 802.11g
a. ) 802.11a
802. 11a runs on 5GHz. 802.11b and 802.11g run on 2.4GHz. 802.11c is not a Wi-Fi standard.
Which should you try first if your device can’t connect to a remembered public wireless network?
Delete the profile and try to connect again.
Which is not true of wireless mesh networks?
a. ) Mesh networks have a single base station
b. ) Mesh networks are best for large enterprise networks
c. ) Mesh networks have one or more beacon/satellite stations
d. ) Mesh networks provide wide coverage in homes and small offices
b.)Mesh networks are best for large enterprise networks
Mesh networks don’t provide the customized configuration required for enterprise-sized networks. All of the other statements are true of wireless mesh networks.
Which is not a wireless radio technology found in computers, tablets, or phones?
a. ) infrared
b. ) Bluetooth
c. ) RFID
d. ) NFC
a.) infrared
Infrared is a rarely-used wireless technology that communicates with infrared light, not radio waves. Bluetooth, RFID and NFC are all wireless radio technologies.
Which is most likely to prevent a device from connecting to a previously-used Wi-Fi network?
a. ) The antenna/s are poorly orientated
b. ) The SSID has changed
c. ) Too many devices are accessing the WAP
d. ) The WAP is disconnected from the internet
b.) The SSID as changed
The most likely answer is that the SSID changed. Poor antenna orientation may reduce speed or range. Too many devices using the WAP are likely to cause low or intermittent connectivity. Even if a WAP is disconnected from the Internet, devices can still connect to it.
