Quiz
Wireless Networking Sample Questions
This quiz has question types that open in the usual player.
Questions in this quiz (17)
1(1) Outline five characteristics of RF waves.
• [blank_start]Propagation[blank_end]
[blank_start]• Speed[blank_end]
• [blank_start]Wavelength[blank_end]
• [blank_start]Frequency[blank_end]
• [blank_start]Radio Communication[blank_end]- APropagation
- B• Speed
- CWavelength
- DFrequency
- ERadio Communication
2(2) Deliniate some of the issues that may need to be considered when extending an existing wireless LAN
Interference
All wi-fi problems are caused by [blank_start]interference.[blank_end] This is because majority of devices operate on the [blank_start]2.4Ghz frequency band[blank_end] which is used by other devices such as Bluetooth headsets, baby monitors and game controllers. Also counting other wireless networks competing with your own.
Speed
Slow internet connections can be caused by a number of factors:
• Your router may be too far away from the [blank_start]master socket[blank_end]
• [blank_start]Poor quality wiring[blank_end] in your home can cause slow connection
• Your [blank_start]network exchange[blank_end] distance from your home is too far
The simple solution would be to install repeaters in areas where you receive poor reception
Security
Security is the biggest concern when extending an existing wireless LAN. This could potentially increase the risk of an intruder [blank_start]stealing packets of data[blank_end] out of the air. The solution would be to ensure that your wireless connection uses [blank_start]WEP[blank_end] which is an [blank_start]encryption protocol[blank_end] for wireless networks.
Cost
Initially it is expensive to extend a wireless LAN as this means installing more [blank_start]access points.[blank_end] Although if you are moving locations it will save money as you won’t have to wire an entire new building. Instead you can [blank_start]pick up the access points[blank_end] and go.- Ainterference.
- B2.4Ghz frequency band
- Cmaster socket
- DPoor quality wiring
- Enetwork exchange
- Fstealing packets of data
- GWEP
- Hencryption protocol
- Iaccess points.
- Jpick up the access points
3(3) Explain and analyse the operation of spreading code in spread-spectrum communications.
The concept of CDMA is based around the fact that a data sequence is [blank_start]multiplied[blank_end] by a spreading code which [blank_start]increases[blank_end] the bandwidth of the signal.
Then within the receiver the same spreading code or sequence is used to [blank_start]extract[blank_end] the required data.- Amultiplied
- Bincreases
- Cextract
4|(4) Critically differentiate between the two access protocols CSMA/CA and CSMA/CD. Explain why the IEEE802.11 standards use CSMA/CA and not CSMA/CD.
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is a protocol for carrier transmission in [blank_start]802.11 networks[blank_end].
In CSMA/CA, when a node receives a packet that is to be sent, it [blank_start]checks[blank_end] if the [blank_start]channel is clear[blank_end] (no other node is transmitting at the time). If the channel is clear, then the [blank_start]packet is sent[blank_end]. Thus it reduces the speed time of the packet reaching its destination.
CSMA/CD (Carrier Sense Multiple Access/Collision Detect) is the protocol for carrier transmission access in [blank_start]Ethernet networks.[blank_end]
On Ethernet, any device can try to send a frame [blank_start]at any time.[blank_end] Each device senses if the line is idle and available to be used. If it is, the device begins to transmit its first frame.
CSMA/CA vs CSMA/CD in 802.11
Pretty much all of the standard IEEE 802.11 (AKA WiFi) devices run at [blank_start]half duplex[blank_end]. Half duplex means the radio can transmit and receive but it can only do one of these things at any moment in time.- A802.11 networks
- Bchecks
- Cchannel is clear
- Dpacket is sent
- EEthernet networks.
- Fat any time.
- Ghalf duplex
5(6) Distinguish at least two characteristics of an ad-hoc wireless network
[blank_start]Mobile Ad hoc networks[blank_end] (MANETs)
A mobile ad hoc network (MANET) is a continuously [blank_start]self-configuring,[blank_end] [blank_start]infrastructure-less[blank_end] network of mobile devices connected without [blank_start]wires.[blank_end]
[blank_start]Smart Phone Ad hoc Networks[blank_end] (SPANs)
SPANs leverage the [blank_start]existing hardware[blank_end] (primarily Bluetooth and Wi-Fi) in commercially available smart phones to create [blank_start]peer-to-peer[blank_end] networks without relying on cellular carrier networks, wireless access points, or traditional network infrastructure.- AMobile Ad hoc networks
- Bself-configuring,
- Cinfrastructure-less
- Dwires.
- ESmart Phone Ad hoc Networks
- Fexisting hardware
- Gpeer-to-peer
6(7) Critically differentiate the Bluetooth transmitter classes in terms of range and transmit power.
• If you wish to communicate over the [blank_start]100m[blank_end] range, you will need a [blank_start]class 1[blank_end] Bluetooth device at both ends.
• If you wish to communicate over the [blank_start]10m[blank_end] range, you can have a class 1 or [blank_start]class 2[blank_end] device at both ends.- A100m
- Bclass 1
- C10m
- Dclass 2
7(8) Characterise how scatternets are formed and outline two drawbacks of scatternets.
• A group of between two and [blank_start]ten non-synchronized[blank_end] piconets that connect through a common device that serves as a [blank_start]bridge[blank_end] between the piconets
• To communicate across a scatternet, a device must support [blank_start]point-to-multipoint[blank_end] communications
Drawbacks
• There are very few actual implementations of scatternets due to [blank_start]limitations[blank_end] of Bluetooth and the [blank_start]MAC address[blank_end] protocol.
• Devices without [blank_start]point-multipoint communications[blank_end] cannot form a scatternet- Aten non-synchronized
- Bbridge
- Cpoint-to-multipoint
- Dlimitations
- EMAC address
- Fpoint-multipoint communications
8(9) Differentiate the two types of scanning that are supported by IEEE802.11 WLANs.
Active Scan
During an active scan, the client radio transmits a [blank_start]probe request[blank_end] and listens for a [blank_start]probe response[blank_end] from an AP.
Passive Scan
With a passive scan, the client radio listens on each channel for [blank_start]beacons[blank_end] sent by an AP. A passive scan generally takes more time, since the client must [blank_start]listen and wait for a beacon[blank_end] versus actively probing to find an AP.- Aprobe request
- Bprobe response
- Cbeacons
- Dlisten and wait for a beacon
9(a) Briefly illustrate and describe, with the aid of a diagram, the ‘hidden node’ problem for wireless networks.
In wireless networking, the hidden node problem occurs when a [blank_start]node is visible[blank_end] from a wireless access point (AP), but not from other [blank_start]nodes communicating[blank_end] with that AP. This leads to difficulties in media access control.
(b) Demonstate and evaluate using a diagram how the RTS/CTS handshake can be used to prevent this problem causing errors.
RTS/CTS is an additional method to implement [blank_start]virtual carrier sensing[blank_end] in Carrier sense multiple access with collision avoidance (CSMA/CA). By default, 802.11 relies on [blank_start]physical carrier sensing[blank_end] only which is known to suffer from the hidden node problem.
- Anode is visible
- Bnodes communicating
- Cvirtual carrier sensing
- Dphysical carrier sensing
10(11) Characterise two examples of where wireless applications can be used in the medical and healthcare industry.
GPS tracking systems where emergency services can [blank_start]detect locations[blank_end] of patients more efficiently.
Patient monitoring systems such as [blank_start]heart monitor[blank_end], [blank_start]x-rays[blank_end] to name just a few.- Adetect locations
- Bheart monitor
- Cx-rays
11(13) Distinguish the three required and at least one of the optional functions performed by the MAC layer on an 802.11x infrastructure network
IEE 802.11 x is a set of [blank_start]MAC & PHY[blank_end] specifications for implementing a WLAN.
• MAC manages and maintains communications between 802.11 stations by [blank_start]coordinating access[blank_end] to a shared radio channel
• It uses the [blank_start]PHY layer[blank_end] to perform tasks such as [blank_start]carrier sensing[blank_end], [blank_start]transmission[blank_end] and receiving of 802.11 [blank_start]frames[blank_end]
• It defines two forms of medium access, [blank_start]distributed coordination function[blank_end] (DCF) and [blank_start]point coordination function[blank_end] (PCF)- AMAC & PHY
- Bcoordinating access
- CPHY layer
- Dcarrier sensing
- Etransmission
- Fframes
- Gdistributed coordination function
- Hpoint coordination function
12(14) Deliniate the different methods that can be used to form a Bluetooth piconet.
A Bluetooth piconet connects up to [blank_start]8 devices[blank_end] in active mode and up to [blank_start]255 devices[blank_end] in parked mode. Bluetooth piconets are combined into a [blank_start]scatternet.[blank_end]
There are two methods to which piconets are formed:
• Basic piconet channel: This Bluetooth connection channel is used only when all [blank_start]79 channels[blank_end] are used within the [blank_start]hop-set[blank_end] - it is now rarely used as the Adaptive piconet channel is more often used as it provides greater flexibility.
• Adapted piconet channel: This Bluetooth connection channel is used more widely and allows the system to use a [blank_start]reduced hop-set[blank_end], i.e. between 20 and 79 channels. Piconet channels are the only channels that can be used to transfer user data.- A8 devices
- B255 devices
- Cscatternet
- D79 channels
- Ehop-set
- Freduced hop-set
13(15) Critically differentiate between AM and FM modulation.
AM (or Amplitude Modulation) and FM (or Frequency Modulation) are ways of [blank_start]broadcasting[blank_end] radio signals. Both transmit the information in the form of [blank_start]electromagnetic[blank_end] waves.
In AM, a radio wave is modulated in [blank_start]amplitude[blank_end] by the signal that is to be transmitted. The [blank_start]frequency[blank_end] and phase remain the same.
In FM, a radio wave is modulated in [blank_start]frequency[blank_end] by the signal that is to be transmitted. The [blank_start]amplitude[blank_end] and phase remain the same.- Abroadcasting
- Belectromagnetic
- Camplitude
- Dfrequency
- Efrequency
- Famplitude
14(16) Distinguish three advantages of an infrastructure WLAN over an ad-hoc wireless network.
• Infrastructure mode is ideal if you’re setting up a more [blank_start]permanent network[blank_end].
• [blank_start]Extend[blank_end] your wireless network's range.
o Placing an access point in between two wireless network adapters [blank_start]doubles[blank_end] their range.
• [blank_start]Share[blank_end] the Internet.
o Probably the most useful device in a simple wireless LAN is an access point with a [blank_start]built-in router[blank_end] and [blank_start]firewall.[blank_end] The router allows you to share Internet access between all your computers, and the firewall hides your network- Apermanent network
- Bdoubles
- CShare
- DExtend
- Ebuilt-in router
- Ffirewall.
15(17) Characterise the primary function of the common MAC layer used in all 802.11x standards.
[blank_start]Scanning[blank_end] is one the functions performed by the MAC layer. It defines both [blank_start]passive[blank_end] and [blank_start]active[blank_end] scanning where a radio NIC searches for access points.
• [blank_start]Passive[blank_end] scanning is where each NIC scans individual channels to find the best access point signal.
• [blank_start]Access[blank_end] points broadcast a beacon, and the radio NIC receives these beacons while scanning and takes note of the corresponding signal strengths.- AScanning
- Bpassive
- Cactive
- DPassive
- EAccess
16(18) Deliniate some of the considerations involved in deciding between a WLAN and a wired LAN.
Cost
• Initially it is expensive to set up a wireless LAN as this means [blank_start]installing access points[blank_end]. Although if you are moving locations it will save money as you won’t have to wire an entire new building. Instead you can [blank_start]pick up[blank_end] the access points and go.
Interference
• All wi-fi problems are caused by [blank_start]interference[blank_end]. This is because majority of devices operate on the [blank_start]2.4Ghz frequency band[blank_end] which is used by other devices such as Bluetooth headsets, baby monitors and game controllers. Also counting other wireless networks competing with your own.
Security
• Security is the biggest concern with wireless LAN. This could potentially increase the risk of an intruder [blank_start]stealing packets of data[blank_end] out of the air. The solution would be to ensure that your wireless connection uses [blank_start]WEP[blank_end] which is an [blank_start]encryption protocol[blank_end] for wireless networks.- Ainstalling access points
- Bpick up
- Cinterference
- D2.4Ghz frequency band
- Estealing packets of data
- FWEP
- Gencryption protocol
17(20) Distinguish five criteria that should be analysed when deciding whether Bluetooth or IR is a better solution for a given WPAN.
[blank_start]Versatility[blank_end]: Bluetooth devices could [blank_start]work together[blank_end]; whereas infrared devices need to be [blank_start]specially designed[blank_end] for specific devices.
[blank_start]Orientation[blank_end]: Infrared devices are [blank_start]direct line-of-sight[blank_end]; whereas Bluetooth devices could communicate even in times of separation by obstacles.
[blank_start]Security[blank_end]: Bluetooth is [blank_start]less secure[blank_end] than infrared due to the nature; whereas infrared signals could only be [blank_start]intercepted[blank_end] by a device.
[blank_start]Range[blank_end]: [blank_start]Class 3[blank_end] bluetooth devices works at about 30 feet; while infrared is rated at 3 feet.
[blank_start]Connectivity:[blank_end] [blank_start]One-to-one[blank_end] connections are made by infrared devices, while Bluetooth devices can form when all the devices have [blank_start]identified[blank_end] themselves to each other.- AVersatility
- Bwork together
- Cspecially designed
- Ddirect line-of-sight
- Eless secure
- FSecurity
- GOrientation
- Hintercepted
- IRange
- JClass 3
- KConnectivity:
- LOne-to-one
- Midentified
Information
- Description
- Bachelors Computer Science (Wireless Networking) Quiz on Wireless Networking Sample Questions, created by Ian Arbuckle on 05/01/2016.
- Author
- Ian Arbuckle
- Language
- English
- Views
- 2
- Tags
- Rating
- No ratings yet Rate this quiz