Tuesday, September 27, 2011

Wi-Fi interview Questions and Answers

Following are the frequently asked Wi-Fi/wifi interview questions and answers. If you have any questions or answers please share with us, we create a unique page for Wi-Fi.

what is Wi-Fi?

WiFi refers to the Wireless connection based local network that is set up to a very restricted range. IEEE maintains the standard for the wireless connection based networks. Wi-Fi stands for Wireless Fidelity an represents the signal transmission mechanism over distances without physical wires.

What are the advantages of Wi-Fi?

mobility( access data while moving) , easy to install( places where wires cannot be put), Flexibility ( helps in quick form of the connection). less cost ( with less money bridge can be created).

what are wireless tools, why it is required?

Wireless tools are mainly added in Root File System(RFS). Wireless tools are mainly open source project. The communication between Application and Network is done through IOCTL's. IOCTL are input output control for device specific operation. Another advantage is device specific parameters may be changed on the fly without restarting the driver (or Linux).The Wireless Tools (WT) is a set of tools allowing to manipulate the Wireless Extensions.

few of the tools are

iwconfig manipulate the basic wireless parameter.
iwlist allow to initiate scanning and list frequencies, bit-rates, encryption keys.
allow to get per node link quality
iwpriv allow to manipulate the Wireless Extensions specific to a driver (private).

for e.g.
iwpriv ra0 set AuthMode=OPEN.

How to compile Wi-Fi driver and insert?

There are different ways to compile Wi-Fi driver depends on the way it implemented. Mostly third party drivers are compiled with the following steps.

select the mode.
select the appropriate toolchain.
enable or disable certain features from the configuration file.
compile the driver with proper kernel source in the location.
insert the module and put the wireless tools in RFS.

what are the steps in Wi-Fi connection establishment?

When Wi-Fi station requires connection, It will start associating with the access point using the Wi-Fi configuration information called as SSID, mode, channel no, MAC address, authentication type and key.

Initialization: Initialization of Wi-Fi device in particular mode named as a,b,g and n.

Scanning: Scanning the list of accesspoints with in the coverage area.

Authentication : Authenticating the station with the Access point depending on the authentication mode in Access point and the key supplied by the user.

Association : Joining with the access point to transmit data to and fro.

Network configuration: After successfully get associated with Accesspoint, we need to configure IP address for the transmission of data using TCP/IP layer.

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