September 17, 2021

TECH HYME

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Wireless Networks – Questions With Answers

8 min read
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Since the early 1990s, the wireless communications field has witnessed explosive growth. The wide range of applications and existing new technologies nowadays stimulated this enormous growth and encouraged wireless applications.

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Wireless networks always play a crucial role in the lives of people at work, home, and public places. Even though a wireless network has a simple purpose, which is to provide connections between users and information sources without the use of wires, critical concepts of wireless networks must be mastered before understanding how they operate.

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This article presents a set of 80 questions (with answers) related to wireless networks:

1) What is a distinguishing attribute of a wireless network as compared to a general wireless communication system?
Answer: In a wireless network, communications takes place between computer devices.

2) What types of information does a wireless network support?
Answer: E-mails, messages, web pages, database records, streaming video, and voice.

3) What are the four types of wireless networks?
Answer: Wireless PAN, LAN, MAN, and WAN.

4) What is the typical maximum range of a wireless PAN?
Answer: 50 feet.

5) True or false: A wireless PAN consumes little power from small handheld computer devices.
Answer: True.

6) What is a common standard for wireless LANs?
Answer: IEEE 802.11 or Wi-Fi.

7) What relatively new standard applies to wireless MANs?
Answer: IEEE 802.16.

8) Why do wireless WANs not effectively satisfy requirements for indoor wireless networks?
Answer: Wireless WAN systems are generally installed outdoors, and the signals lose strength before reaching the inside of the facility.

9) What is a common application of wireless networks in homes and small offices?
Answer: Sharing Internet connections among multiple, mobile computers is a common application.

10) What are examples of applications for wireless WANs?
Answer: Access to Internet applications from outdoor locations, realestate transactions, field-service and sales calls, vending-machine status, and utility-meter reading are a few examples.

11) Which wireless NIC form factors are best for small wireless computer devices?
Answer: PC Card, Mini-PCI, and CompactFlash.

12) What are examples of elements that impair the propagation of wireless communications signals through the air medium?
Answer: Rain, snow, smog, and smoke.

13) What is the primary purpose of a base station?
Answer: Interfaces the wireless communications signals traveling through the air medium to a wired network.

14) What are common features of wireless middleware?
Answer: Optimization techniques, intelligent restarts, data bundling, screen shaping and reshaping, and end-system support.

15) On what layers of the OSI reference model do wireless networks operate?
Answer: Physical layer and data link layer.

16) How is throughput different from data rate?
Answer: Throughput doesn’t include overhead of protocols.

17) True or false: A computer device stores data in analog form.
Answer: False.

18) A wireless NIC must convert the information into what type of signal before transmission through the air medium?
Answer: Analog.

19) Which medium access protocol is common with wireless networks?
Answer: CSMA.

20) Explain how the ARQ form of error control works.
Answer: The receiving wireless NIC performs error checking and sends a request to the sending wireless NIC to retransmit the frame if errors are found.

21) RF signals offer relatively short range as compared to light signals. True or false?
Answer: False.

22) What type of weather impacts RF signals the most?
Answer: Heavy rain.

23) Why does interference cause errors in wireless networks?
Answer: The interference causes the receiver to misunderstand the signal because two signals are present at the same time.

24) What are sources of RF interference?
Answer: General examples include cordless phones, microwave ovens, and Bluetooth devices.

25) Multipath affects higher data rates more than lower data rates for 2.4 GHz systems. True or false?
Answer: True. The receiver has difficulties with differentiating one bit from another when demodulating high data rate signals because the bits are close together.

26) What is meant by a diffused infrared light system?
Answer: A system that emits light in all directions that reflects off of the ceiling and walls.

27) Approximately up to what range do direct infrared systems operate?
Answer: 1 mile.

28) How does modulation make it possible to transmit information through the air?
Answer: Modulation superimposes an information signal onto a carrier signal that has a frequency suitable for propagating through the air.

29) What attributes of a signal does QAM change in order to represent information?
Answer: Amplitude and phase.

30) Spread spectrum generally requires user licenses. True or false?
Answer: False.

31) What form factors are common for wireless PAN radio cards?
Answer: PC Card and CF.

32) What application can strongly benefit through the use of a wireless USB adapter (also referred to as a wireless dongle)?
Answer: Any application that can benefit from interfacing with a PC or laptop through the USB port, such as PDA, wireless mouse, and wireless digital camera for synchronization purposes.

33) When would the use of a wireless PAN router make sense?
Answer: For applications limited to the size of a room, such as in homes and small offices.

34) What is the general maximum coverage area of a wireless PAN?
Answer: Within 30 feet, such as within a room.

35) Which IEEE standards group uses Bluetooth as the basis for the standard?
Answer: 802.15.

36) In what frequency band does Bluetooth operate?
Answer: 2.4 GHz.

37) What is the primary issue of using Bluetooth around 802.11 wireless LANs?
Answer: They both operate in the same 2.4 GHz frequency band, which can result in interference and degradation in performance.

38) A Bluetooth-enabled device is always transmitting. True or false?
Answer: False.

39) What is the highest possible data rate of an IrDA device?
Answer: 4 Mbps.

40) What is a benefit of IrDA as compared to Bluetooth?
Answer: IrDA is immune from RF interference with wireless LANs.

41) Which wireless LAN component is most commonly used in home and small offices?
Answer: Wireless LAN router.

42) What is the primary difference between an access point and a wireless LAN router?
Answer: A wireless LAN router actually routes packets to their destination. Access points don’t implement DHCP and NAT. Routers do implement DHCP and NAT.

43) When would the use of a wireless LAN repeater make sense?
Answer: When extending the range of an access point or router to an area where wires can’t be run feasibly.

44) How does a wireless LAN radio NIC identify with which access point to associate?
Answer: The radio NIC listens for beacons being sent periodically by each access point and associates with the access point having the strongest beacon signal.

45) WEP is a mandatory encryption mechanism. True or false?
Answer: False.

46) In what frequency band does 802.11a operate in?
Answer: 5 GHz.

47) How many non-overlapping channels are available with 802.11b wireless LANs?
Answer: Three.

48) True of false: 802.11g operates at up to 54 Mbps and interoperates with 802.11b.
Answer: True.

49) Which 802.11 frequencies are available almost worldwide?
Answer: 2.4 GHz (802.11b and 802.11g).

50) What does Wi-Fi provide?
Answer: A product having Wi-Fi certification will interoperate with other products that have Wi-Fi certification, regardless of the manufacturer.

51) Why does a wireless MAN offer good return on investment?
Answer: Wireless MANs eliminate the need to install expensive cabling or lease communications circuits.

52) A learning bridge forwards all packets. True or false?
Answer: False.

53) What is the primary difference between a bridge and an access point?
Answer: A bridge connects networks together. An access point connects end users.

54) What are examples of semidirectional antennae?
Answer: Patch and Yagi.

55) In regards to beamwidth, what is the primary difference between a semidirectional and highly directional antenna?
Answer: A highly directional antenna has a much narrower beamwidth, which increases range if the power remains constant.

56) What is an example of a highly directional antenna?
Answer: Dish antenna.

57) What polarization would be most effective at a receiver if the transmitter were using vertical polarization?
Answer: Vertical polarization.

58) What are the advantages of using point-to-multipoint systems versus point-to-point for interconnecting multiple sites?
Answer: Point-to-multipoint can be less expensive and easier to add more sites.

59) What are the advantages of using packet radio for wireless MANs?
Answer: Packet radio routers don’t require any cabling between them, and the system is relatively survivable because packets can take a different route if a router becomes inoperative.

60) Which standards do wireless MANs employ?
Answer: 802.11, Wi-Fi, and 802.16.

61) What types of user devices are most common with wireless WANs?
Answer: Laptops, PDAs, and mobile phones.

62) Why do wireless WAN operators always charge for services?
Answer: Wireless WANs are expensive to install.

63) Why must you be careful when selecting a wireless WAN radio NIC for your user device?
Answer: There are many different types of wireless WANs that are not compatible with each other.

64) What is an advantage of a satellite system?
Answer: It can cover vast areas. A single satellite can cover roughly one-third of the Earth’s surface.

65) Which generation of cellular systems offers data rates up to 2 Mbps?
Answer: Third generation (3G).

66) Which type of wireless WAN system is most common?
Answer: Cellular systems.

67) Which of the two following cellular systems offers the highest data rates: GPRS or UMTS?
Answer: UMTS.

68) What is the primary issue with meteor burst communications?
Answer: Low data rates.

69) True or false: FDMA requires users to take turns transmitting signals.
Answer: False.

70) How does CDMA keep users from interfering with each other?
Answer: Each user transmits using a different code.

71) What are the three major security threats of a wireless network?
Answer: Traffic monitoring, unauthorized access, and DoS.

72) What is the primary means for guarding against traffic monitoring?
Answer: Utilize encryption.

73) How do you keep hackers from gaining access to company resources through the wireless network?
Answer: Incorporate the use of effective authentication.

74) What method will help alleviate the implications of a successful DoS attack?
Answer: Have an alternative plan to carry on business in a manner that doesn’t require the use of the wireless network.

75) Why is WEP not acceptable for protecting sensitive information?
Answer: Hackers are able to crack the WEP encryption algorithm through the use of publicly available tools.

76) How is TKIP different than WEP?
Answer: TKIP make use of a dynamic key distribution mechanism that updates keys periodically, whereas WEP makes use of static keys that don’t change.

77) WPA uses TKIP and is a subset of the 802.11i standard. True or false?
Answer: True.

78) Why is the use of MAC address filters not effective?
Answer: It’s difficult to manage and easy to spoof.

79) What is a rogue access point, and why does it pose a problem?
Answer: A rogue access point does not have any security features set and is put in by a hacker or employee. The rogue access point offers an open port to the network for hackers to exploit.

80) What should you install on a laptop that a user will utilize on a public wireless LAN to avoid unauthorized people from accessing files on the laptop?
Answer: Personal firewall.

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