WiFi Interview Questions and Answers - WiFi FAQs

What is Piggybacking in context to Wi-Fi?

Piggybacking is a term which states that something that is riding on the back of something else to complete his/her motive, just like similar to an idiom putting gun to another’s shoulder and performing Hunting, so piggybacking is a term used to refer to access of a wireless internet connection by bringing one’s own computer within the range of another’s wireless connection, and using that service without the subscriber’s explicit permission or knowledge. It is a legally and ethically controversial practice, with laws that vary in jurisdictions around the world. Piggybacking is an unauthorized tapping into another’s connection with a public utility.

For e.g.- So piggybacking can take place like when I am accessing the wireless connection of my neighbour Wi-Fi without his/her knowledge by hacking his static ip address, then it would be possible for me to access the Wi-Fi connection of others.

What are the recommended channels if you are setting up three WLANs and want minimum interference over there?

1) There is a need of selecting the channels for setting up WLANs, to communicate; all the components of a Wi-Fi network must use the same channel. In the Wi-Fi network in infrastructure mode (using an access point), it depends on the channel set at the access point.

2) For better results when using Wi-Fi, it is necessary to adjust the channel on the access point as well as configured on the client, to take the least use channel in your neighbourhood.

3) To do this you can use software such as NetStumbler, which will list the neighbourhood Wi-Fi networks and channels used.

Note:- The channels most frequently used to select one as free as possible.

So the recommended channels are as follows:-

Channel 1: 2.412 MHz

Channel 2: 2.417 MHz

Channel 3: 2.422 MHz

Channel 4: 2.427 MHz

Channel 5: 2.432 MHz

Channel 6: 2.437 MHz

You can choose from these channels while setting up the WLANs.

How to crack Wi-Fi network, if you are using WEP (Wired Equivalent Privacy) Password with backtrack?

1) The first line of defense of your Wi-Fi network is encryption, which encodes the data transmitted between your PC and your wireless router.

2) WEP abbreviates (Wireless Encryption Protocol). It is a less-secure protocol than WPA (Wireless Protected Access). Since WEP is relatively easy to crack, so you have to use the same form on all devices on your network. If you have an older router that supports WEP only you’ll be best safest if you use 128-bit bit WEP keys but also check the manufacturer’s Web site for a firmware update that will add WPA support.

3) Two of the most popular programs used for actually cracking the WEP key are Airsnort and Aircrack. Airsnort can be used with the .dump files that Kismet provides; and Aircrack can be use with .cap files that Airodump provides.

Differentiate between Ad-Hoc and Infrastructure topology and also explain with their advantages and disadvantages?

Wireless networks typically work in one of two configurations: Ad-Hoc or Infrastructure.

1) Ad-Hoc is Latin meaning “for this purpose” so these are the networks which are basically created for some purpose. So these are the group of workstations which communicate directly witch each other to exchange information. An Ad-Hoc network is also called as a peer to peer network.

Here are some benefits of an Ad-Hoc network are:-

a) The possibilities with Ad-Hoc network are quite endless.
b) Ad-Hoc networks are simple to set up.
c) Ad-Hoc networks are inexpensive.
d) Ad-Hoc networks are fast.

Disadvantages of an Ad-Hoc network are as follows:-

a) It is not able to get into the mainstream wired local area network.
b) It needs more technology to support their reliability.
c) As the network increases its speed slows down considerably.

2) In Infrastructure mode, network includes an access point when the wireless clients connect to an access point, which in turn bridges to a network. Infrastructure network can pass information through a central information hub which can be both, hardware or software device on a computer. So under this devices in a wireless network are set up to communicate through an access point.

An infrastructure network enables you to:-

a) In this you do not have to control over the path your data takes.
b) Connect to a wired network.
c) Extend your wireless network’s range.
d) Utilize roaming ability.

Disadvantages for Infrastructure network are:-

1. Use of more wireless access points.
2. This increase the cost of implementing a wireless network solution.

How do you secure a wireless network?

Key points for securing a wireless network are as follows:-

a) Verify that your PC’s software firewall is turned on, and that Window’s file-sharing feature is off; it’s off by default in Window’s XP with Service Pack 2.

b) Never send bank passwords, credit card numbers, confidential e-mail, or other sensitive data unless you’re sure you’re on secure site: Look for the lock icon in the bottom-right corner of your browser, as well as a URL in the address bar that begins with https. Such sites build in their own encryption.

c) Always turn your Wi-Fi radio off when you're not at a hotspot: Hackers can use it to create peer-to-peer Wi-Fi connections with your computer and access it directly.

d) For better security, consider signing up for a paid subscription to a hotspot network such as Boingo or T-Mobile. Both companies provide connection software that encrypts your sessions automatically.

By attaining these key points you can secure wireless network up to an extent.

What are your preferred tools for WarDriving?

Preferred tools for WarDriving are as follows:-

a) Kismet- Kismet is a 802.11b wireless network sniffer. It is capable of sniffing using almost any wireless card supported in Linux.

b) Airsnort- is one of the first tools to come out discovering insecurity of wireless network. AirSnort is a wireless LAN (WLAN) tool which cracks encryption keys on 802.11b WEP networks. AirSnort operates by passively monitoring transmissions, computing the encryption key when enough packets have been gathered.

c) WEPCrack is Perl based tool. WEPCrack is a tool that cracks 802.11 WEP encryption keys using the latest discovered weakness of RC4 key scheduling.

d) WaveStumbler is console based 802.11 network mapper for Linux. It reports the basic AP stuff like channel, WEP, ESSID, MAC etc.

e) Aircrack yet another WEP cracking tool for Linux courtesy by divine.

How can you configure Wi-Fi network and what are Wi-Fi Protocols?

1) Basically there are many standards of Wi-Fi in the industry but some popular of them are 802.11a, 802.11b, 802.11g/n. With the support of these Wi-Fi protocols we can communicate/interact among the devices at the speed of 5Ghz to 2.4Ghz dual band communication.

2) If we have Wi-Fi nic card so firstly we have to install their drivers and after installation if we have Wi-Fi access point then we can see the signal strength in the right corner below just open that and find the access point to connect, if access point is configured with the security, type the key to connect and enjoy the service.

3) Wi-Fi is technically referred to as the 802.11 protocol. Over time, Wi-Fi has improved, giving rise to different variations of the protocol.

802.11a – This version operates at 54Mbps. It is considered as the favorite wireless LAN protocol for IP telephony.

How is UWB (ultra-wideband) different from Bluetooth, FireWire and Wi-Fi?

- UWB is Radio Frequency technology that transmits binary data, using low energy and short duration impulses over a wide spectrum of frequencies. It delivers data over 15 to 100 meters and does not require a dedicated radio frequency. For example, a UWB signal centered at 5GHz typically extends across 4GHz and 6GHz. At longer distances, UWB data rates drop considerably.

- Bluetooth:- The key difference among UWB and Bluetooth are of range, power, consumption and intended use. It is basically meant for short distances up to (10m). It is low power consuming than UWB.

- Since FireWire is meant to deliver high speed, it is also designed to work with high power drain services. It therefore can provide much more power to the devices that connect to it. It can deliver up to 60 watts of energy. So the only difference here is of power it uses more power than UWB.

- Wi-Fi really wasn’t built to move audio and video, it was built for data traffic where if there’s delay, while UWB is better suited for multimedia for a couple of reasons, i.e. for starters, it’s throughput for surpasses that of Wi-Fi.

Who are the providers and what are the assets available for wireless?

Some of the providers for wireless are as follows:-

a) Wireless Internet- Nationwide Coverage Unlimited
b) Faster Internet on Mobile
c) New 3G BlackBerry
d) Aircel Pocket Internet
e) Reliance 3G Online Offer
f) Cisco Managed Switches

Brand assets are available here for wireless, brand assets can also be applied to m-branding. In particular, three of the assets can be targeted directly for improvement with the m-branding methods that are available today. These are brand awareness, brand associations and brand loyalty.

Wireless networking, or Wi-Fi, can be used to connect computers in a home, and many cities are using technologies to offer free or low cost internet access to residents, what is another name for Wi-Fi?

- IEEE 802.11 is the official name for WIFI wireless specification. It is composed of more than 20 different standards (802.11a, 802.11b, etc), each of which have their own defining characteristics. Since not all standards operate on the same frequency, not all 802.11 devices are compliant with one another, so be sure to consider the compatibility when making your purchasing decision. So this is an alternative name for Wi-Fi which suits all the properties of the Wi-Fi and functioning as well.

- Wireless networking hardware requires the use of underlying technology that deals with radio frequencies as well as data transmission. The most widely used standard is 802.11 produced by the Institute of Electrical and Electronic Engineers (IEEE). This is a standard defining all aspects of Radio Frequency Wireless networking.

Can I mix wireless equipments from different vendors, elaborate on it?

- You can mix wireless equipments from different vendors, but the recommendation is that you should prefer only prescribed vendors, because most wireless networking hardware vendors support the 802.11 standard they can inter operate. However, we recommend verification as the standard is a fairly recent one, and does specify two different methods for wireless communications; Frequency Hopping (FH) and Direct Sequence Spread Spectrum (DSSS or DS), which are not interoperable.

- When purchasing wireless networking hardware from separate vendors be sure to obtain guarantees from the vendors that the hardware will interoperate and follows the standards.

- Within a short time we expect all new wireless cards, like ethernet cards, to become inexpensive, ubiquitous and totally interoperable.

- Also of note is that the latest version of the standard defines 11mbps and 5.5mbps networking, with support for the older standard 1mbps and 2mbps speeds. This provides some compatibility with different or older equipment. Note that this new standard covers DS-type Networks, not FH types.

- Software access points such as InterGate which uses the wireless interface of the host computer should have no compatibility issues with third party wireless hardware, as long as standards are followed. Typically wireless hardware is identified to the software as a network interface, and therefore can be used in the same way as any other network card. So you can choose them from different vendors but keeping these things in mind and then go ahead.

If my computer is connected to wireless LAN, can it communicate with computer on wired LAN as well?

- To do this you will need some sort of bridge between the wireless and wired network. This can be accomplished either with a hardware access point or a software access point. Hardware access points are available with various types of network interfaces, such as Ethernet or Token Ring, but typically require extra hardware to be purchased if your networking requirements change.

- If networking requirements go beyond just interconnecting a wired network network to a small wireless network, a software access point may be the best solution.

- A software access point does not limit the type or number of network interfaces you use. It may also allow considerable flexibility in providing access to different network types, such as different types of Ethernet, Wireless and Token Ring networks. Such connections are only limited by the number of slots or interfaces in the computer used for this task.

- Further to this the software access point may include significant additional features such as shared Internet access, web caching or content filtering, providing significant benefits to users and administrators.

Is it true that Wireless networking is only good for laptop computer?

- Although wireless networking offers obvious benefits to users of laptops who move from location to location throughout the day, there are benefits for users of fixed position computers as well:

- So this is not such that wireless networking is only good for laptop computers but on preference basis it got more than fixed positions, as laptop computers are portable, flexible, ease to use and move.

- Many schools and businesses have unsuitable building layouts or walls that cannot be wired for various reasons making it difficult or impossible to build a wired network. Wireless networking in these environments is a very cost effective alternative also providing future flexibility.

- In cases where a small number of computers are separated from a main network a wireless link may be more cost effective than network cabling although the latter is perfectly feasible.

- Temporary wireless LANs can easily be created for exhibitions, school or business projects, all without any trailing cabling.

What is Wi-Fi technology and over which frequency band it operates?

Wi-Fi technology is a technology used for transmitting a signal using the 802.11 specifications works a lot like it does with a basic Ethernet hub: They’re both two-way forms of communication, and they both use the same frequency to both transmit and receive, often referred to a half-duplex. WLANs used radio frequencies (RFs) that are radiated into the air from an antenna that creates radio waves. These waves can be absorbed, refracted, or reflected by walls, water, and metal surfaces, resulting in low signal strength. So because of this vulnerability to surrounding environmental factors, it’s pretty apparent that wire-less will never offer us the same robustness as a wired network can, but that still doesn’t mean we’re not going to use or run the wireless or Wi-Fi.

What are the different Wi-Fi generations and also explain any one?

The IEEE 802.11 generation is actually only the earliest standard, allowing 1-2 Mbps of bandwidth. Amendments have be made to the original standard in order to optimize bandwidth (these include the 802.11a, 802.11b and 802.11g standards, which are also called 802.11 physical standards) or to better specify components in order to ensure improved security or compatibility.

Name of Generation- 802.11a

Name- WiFi5

Description- The 802.11a standard (called Wi-Fi 5) allows higher bandwidth (54 Mbps maximum throughput, 30 Mbps in practice). The 802.11a standard provides 8 radio channels in the 5 GHz frequency band.
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