Wireless networks eliminate cabling by using radio waves as a network medium.

True / False Questions
 

36. (p. 425) Wireless networks eliminate cabling by using radio waves as a network medium.
TRUE

37. (p. 430) Devices using the 2.4-GHz frequency are the most likely to experience interference from other wireless devices.
TRUE

38. (p. 431) Wi-Fi networks use CSMA/CA.
TRUE

39. (p. 433) The 802.11g specification requires all but hand-held devices to use MIMO.
FALSE

40. (p. 407) Nearby WAPs should use adjacent channels.
FALSE

41. (p. 434) Wireless networks are less secure than wired networks.
TRUE

42. (p. 435) The IEEE 802.1X standard for wireless networks provides for secure authentication and password encryption.
TRUE

43. (p. 436) Wireless data encryption using the WEP standard is the best you can use.
FALSE

44. (p. 437) All standard Ethernet switches support Power over Ethernet (PoE).
FALSE

45. (p. 440) An omnidirectional dipole antenna focuses the radio beam in one direction.
FALSE

46. (p. 425-426) The original 802.11 standard is almost unused today.
TRUE

47. (p. 434) WAPs use an access control list (ACL) to enable or deny specific MAC addresses.
TRUE

48. (p. 434) MAC filtering with a blacklist means you allow only specific computers to join the network.
FALSE

49. (p. 436) WPA2 uses the RC4 cipher.
FALSE

50. (p. 436) WPA2-Enterprise uses a RADIUS server for authentication.
TRUE

Fill in the Blank Questions
 

51. (p. 425) Wireless networks operate at the same OSI layers and use the same protocols as _______________ networks.
wired

52. (p. 425) The IEEE _______________ standard defines how a wireless device communicates and how to secure wireless communication.
802.11

53. (p. 425) _______________ is the common name used for the various implementations of the IEEE 802.11 wireless Ethernet standard.
Wi-Fi

54. (p. 426) All implementations of Wi-Fi require a(n)_______________ name and a(n) _______________ for communication.
shared network; channel

55. (p. 427) _______________ mode is more commonly used than _______________ mode.
infrastructure, ad hoc

56. (p. 427) Ad hoc mode is also known as _______________ mode.
peer-to-peer

57. (p. 429) The _______________ of a wireless network is the same as the MAC address for the WAP.
Basic Service Set Identifier (BSSID)

58. (p. 429) The actual _______________ of a wireless network is affected by environmental factors, such as interference from other wireless devices and solid objects.
range

59. (p. 428) _______________ wireless mode is best suited for business networks or networks offering access to shared, dedicated resources.
infrastructure

60. (p. 430) Early 802.11 standards used the _______________ frequency, while later standards either use that frequency or the _______________ frequency.
2.4-GHz; 5.0-GHz

61. (p. 430) Most WAPs use channels _______________, _______________, and _______________ by default.
1; 6; 11

62. (p. 431) The method used by Wi-Fi devices to access a network without stepping on each other's data packets is _______________.
carrier sense multiple access/collision avoidance (CSMA/CA)

63. (p. 431) Up to this point, the _______________ collision avoidance method is implemented in Wi-Fi devices.
Distributed Coordination Function (DCF)

64. (p. 432) Wireless devices using the _______________ frequency are least likely to run into interference from other wireless devices.
5.0 GHz

65. (p. 432) Despite the superior speed of the _______________ standard, it never enjoyed the popularity of 802.11b.
802.11a

66. (p. 435) A(n) _______________ allows a remote user to connect to a network, providing authentication through a user name and password, and enables an administrator to set a user's rights on a network.
RADIUS server

67. (p. 435) A client computer authenticating using RADIUS is called a(n) _______________.
supplicant

68. (p. 435) When implementing wireless network security, both the _______________ and the _______________ must use the same authentication scheme.
WAP; wireless NICs

69. (p. 443) It is important to _______________ the data frames in a wireless network.
encrypt

70. (p. 437) Switches that support _______________ provide power to devices through an Ethernet port.
Power over Ethernet (PoE)

71. (p. 438) Before installing a Wi-Fi network, be sure to do a(n) _______________ to locate any obstacles you need to overcome.
site survey

72. (p. 430) Before installing a Wi-Fi network, it is important to discover existing wireless signals in order to set both the SSID and the _______________ used to avoid conflicts.
channel

73. (p. 440) _______________ antennas are the typical straight-wire omnidirectional antennas found on most WAPs.
Dipole

74. (p. 441) To increase the ratio of signal increase, or _______________ of a WAP, replace the factory antennas with one or more bigger ones.
gain

75. (p. 441) Create a more focused wireless network, and avoid broadcasting in all directions, by using a(n) _______________.
directional antenna

76. (p. 447) A(n) _______________ wireless bridge can talk to more than one other bridge at a time, connecting multiple network segments.
point-to-multipoint

77. (p. 448) Before leaving a new network installation, you should _______________ the installation.
verify

78. (p. 450) A refrigerator, reinforced wall, metal plumbing, or microwave are some of the items that can cause _______________ for a wireless network.
interference

79. (p. 441) Parabolic, dish, and Yagi are all examples of _______________.
directional antennas

80. (p. 449) Most wireless connectivity problems are caused by either _______________ or _______________.
incorrect configuration; low signal strength

81. (p. 434) When you deny specific computers access to the wireless network, you create a(n) _______________.
blacklist

82. (p. 436) __________ is a streaming cipher that is used in WEP.
RC4

83. (p. 436) A Wi-Fi signal can be disrupted by a radio signal from another device, and this disruption is called __________.
Radio Frequency Interference (RFI)

84. (p. 450) Signal bounce can cause a problem called __________ signals.
multipath

85. (p. 436) The __________ used in WEP is only 24 bits, which contributes to its ease of compromise.
initialization vector (IV)

Essay Questions
 

86. (p. 439) Describe the advantage of using a USB wireless NIC over an expansion card NIC or PC Card NIC. 

The advantage of using a USB wireless NIC over one that is built-in or on an expansion card, or even on a PC Card, is the ability to use an extender cable, allowing the USB NIC to be placed in an optimum location for signal strength.

87. (p. 449) Where can you find the best configuration software for a wireless NIC? 

While Windows systems have wireless NIC configuration software built in, the best configuration software for a wireless NIC is normally the software that comes with it.

88. (p. 426) Briefly describe both the similarities and differences between a wired Ethernet NIC and a wireless Ethernet NIC. 

A wired Ethernet NIC and a wireless Ethernet NIC are alike in that they take data passed down from the upper OSI layers, encapsulate it into data packets, send the packets out on the network media as binary data, and receive data packets sent from other NICs. The main difference is that rather than charging up a network cable with electrical current, as an Ethernet NIC for copper cabling would do, or sending out light pulses, as an Ethernet NIC for fiber optic would, a wireless NIC transmits and receives radio waves.

89. (p. 427) Describe ad hoc mode. 

Ad hoc mode is a wireless mode in which each wireless node is in direct contact with all the other wireless nodes. This is a decentralized free-for-all, without a centralized component. Without such a component, you cannot connect an ad hoc wireless network to other networks, unless one of the ad hoc nodes is running Windows Internet Connection Sharing (ICS) or its equivalent.

90. (p. 428) Describe infrastructure mode. 

Infrastructure mode is a wireless mode in which one or more WAPs connect the wireless network nodes centrally in a star topology. A wireless network in infrastructure mode can connect to wired network segments via a wireless router.

91. (p. 429) Describe factors that affect wireless network speeds. 

Factors that affect wireless network speeds are the standards used, the distance between nodes and the WAP, interference from other wireless devices, and solid objects blocking the signal.

92. (p. 429) Define Service Set Identifier (SSID). 

A service set identifier is a 32-bit identification string that is inserted into the header of each data packet processed by a WAP in a BSS. All Wi-Fi devices must have the same SSID in order to communicate in a single Wi-Fi network.

93. (p. 429) Distinguish between a Service Set Identifier (SSID) and an Extended Service Set Identifier (ESSID). 

While a Service Set Identifier is a 32-bit identification string inserted into the header of each data packet processed by a WAP in a BSS, an Extended Service Set Identifier is an SSID that applies to a Wi-Fi network that has multiple WAPs (an EBSS or ESS). However, most manufacturers use the term SSID for either identifier.

94. (p. 430) Define spread-spectrum radio waves. 

The phrase spread-spectrum radio waves describes the broadcasting of data in small, discrete chunks over the different frequencies available within a certain frequency range.

95. (p. 430) Describe the direct-sequence spread-spectrum (DSSS) wireless broadcasting method. 

The DSSS broadcasting method sends data out on different frequencies at the same time.

96. (p. 430) Describe the frequency-hopping spread-spectrum (FHSS) wireless broadcasting method. 

The frequency-hopping spread-spectrum (FHSS) wireless broadcasting method sends data on one frequency at a time, constantly shifting (or hopping) frequencies.

97. (p. 430) Describe the orthogonal frequency division multiplexing (OFDM) wireless broadcasting method. 

The orthogonal frequency division multiplexing (OFDM) method combines the multiple frequencies of DSSS with the frequency-hopping capability of FHSS.

98. (p. 430) Define a channel. 

A channel is a portion of the available spectrum.

99. (p. 433) Describe transmit beamforming, including its purpose and the types of devices that support this technology. 

Transmit beamforming is a multiple-antenna technology used in many 802.11n WAPs to help minimize or eliminate dead spots.

100. (p. 434) Explain why wireless network communications is inherently less secure than wired communications. 

While wired communications occur on network cabling, wireless communications travels on radio waves, which are easily captured by unscrupulous people.

101. (p. 435) Describe the role of a WAP in a wireless network using a RADIUS server for authentication. 

The wireless client computer (supplicant) requests permission to access the network by contacting the WAP, which has the role of a Network Access Server (NAS). As an NAS, the WAP contacts the RADIUS server to see if the supplicant is in the security dataset, and if the user name and password are correct. After the RADIUS server confirms this, the remote user gets access to the network.

102. (p. 438) Describe possible interference sources and obstructions to wireless signals that you should discover and map in a site survey. 

Interference sources and obstructions to wireless signals that you should discover and map in a site survey include appliances, such as refrigerators and microwaves, reinforced walls, metal plumbing, and other obstructions to radio waves.

103. (p. 438) Describe some steps you might need to take to avoid dead zones in a wireless network. 

You may need to upgrade to the latest equipment, such as 802.11n, which has three antennas, and/or you may need to plan on using multiple WAPs in the wireless network.

104. (p. 439) When setting up an ad hoc network, what tasks must you perform beyond setting each NIC to ad hoc mode? 

You need to assign the same SSID to each host in the ad hoc network. You must also ensure that no two NICs have the same IP address, and configure all NICs to use the same channel (which should be one chosen to avoid interference from other wireless devices). Finally, configure File and Print Sharing on all the hosts that will be sharing their files and/or printers.

105. (p. 439-440) Describe the tasks for configuring a wireless network for infrastructure mode. 

The tasks involved in configuring a wireless network for infrastructure mode include performing a site survey, determining the optimum placement for the WAP or WAPs based on the findings of the site survey, configuring the WAP with the proper settings for the SSID, security, and encryption, and configuring each NIC for the same.

106. (p. 441) Explain a situation in which an omnidirectional antenna would not be the optimum solution for a WAP. 

A simple omnidirectional antenna may not work in the case of the size of the network space exceeding a signal and bleeding out, which is a security threat to your network. This type of antenna may not work where obstacles produce dead spots. Finally, dead spots may require other solutions.

107. (p. 442) What are the trade-offs you must consider when modifying the beacon interval on a WAP? 

The trade-offs are less traffic, if you increase the interval of the beacon traffic, and a longer beacon interval will also create a delay in the speed at which devices can negotiate to get on the network.

108. (p. 434) Explain MAC address filtering. 

MAC address filtering is the use of a wireless NIC's MAC address to either allow or deny it access to a wireless network. A WAP has a configuration setting that allows an administrator to turn this on, and then create a list of allowed users by MAC address or a similarly defined list of denied users.

109. (p. 436) Describe what you must do to turn on and configure encryption in a wireless network. 

Encryption is turned on at the WAP and the initial configuration is done there as you generate a unique security key. Next, you configure each of the client NICs with the same key information. The encryption level, key, and passphrase must match on the WAP and clients, or the clients will not get access to the network.

110. (p. 445) When installing an 802.11n wireless network in an area with overlapping 802.11b and 802.11g networks, how can you avoid conflicts for your 802.11n network? 

When installing an 802.11n wireless network in an area with overlapping 802.11b and 802.11g traffic, set the 802.11n network to use the 5-GHz frequency rather than the 2.4-GHz frequency of the other networks. An 802.11n network can use either frequency.

111. (p. 448) What must you do after setting a WAP to not broadcast the SSID? 

If you configure a WAP to not broadcast the SSID, you will need to manually configure the wireless clients with the SSID because they will not be able to pick it up from broadcasts.

112. (p. 446) Describe the usual procedure for installing the driver and configuration utility for a wireless USB device. 

The usual procedure for installing the driver and configuration utility for a wireless USB NIC is to first install the driver and software, and then connect the USB wireless NIC.

113. (p. 449) How can you quickly determine if a wireless NIC is passing data packets to and from the network? 

You can tell if a wireless NIC is passing data packets to and from the network by checking the link light.

114. (p. 448) Describe the three questions you should ask yourself when troubleshooting a wireless networking problem. 

The three questions are: who, what, and when. Who is affected? What is the nature of the problem? When did the problem start?

115. (p. 449) How can you quickly determine the signal strength of a wireless NIC on your wireless network? 

Most NICs have a configuration utility with a status icon in the System Tray of a Windows computer. This icon normally shows the signal strength. If there is no status icon, then open the configuration utility to find the status information including the signal strength.

116. (p. 434) Describe whitelisting and blacklisting. 

WAPs use an access control list (ACL) to enable or deny specific MAC addresses. This is called MAC filtering. MAC filtering with a whitelist means you allow only specific computers to join the network. When you deny specific computers, you create a blacklist. Since MAC addresses are easily spoofed, this is not a very effective security measure,

117. (p. 445) Discuss why the using the 5-GHz range for wireless networking produces less interference than the 2.4-GHz range. 

The 5.0-GHz range is much less crowded than the 2.4-GHz range, reducing the chance of interference from devices such as telephones and microwave ovens. Too much signal interference can increase latency, making the network sluggish and slow to respond. Running in the 5.0-GHz range greatly reduces this problem.

118. (p. 431) Why do wireless networks not use CSMA/CD to detect and avoid network collisions? 

Modern wired networks use switches running in full-duplex mode, so they don't have to worry about collisions. In this environment, CSMA/CD is disabled when using full-duplex. Wireless networks don't have this luxury for two reasons. First, radio is a half-duplex transmission method, since a wireless device cannot listen and send at the same time. Secondly, there are times where wireless clients may not know about the existence of another client due to signal strength. Wireless networks, for those reasons, use CSMA/CA to avoid collisions.

119. (p. 433) Describe channel bonding. 

Later 802.11g manufacturers incorporated channel bonding into their devices, enabling the devices to use two channels for transmission. Channel bonding was not part of the 802.11g standard, but rather a proprietary technology pushed by various companies to increase the throughput of their wireless networks. Both the NIC and the WAP, therefore, had to be from the same company for channel bonding to work.

120. (p. 435) How does a RADIUS server respond to an authentication request from a supplicant? 

If the supplicant sends an authentication request, and the user name and password are correct, the RADIUS server sends a packet back to the supplicant, through the WAP, with an Access-Accept code and an Authenticator section that proves the packet actually came from the RADIUS server.