ISM 4220 Oliveira Chapter 6
10) Attenuation with distance is faster with ________. A) radio transmission B) UTP transmission C) Both A and B D) Neither A nor B
A
2) Wireless network standards come from ________. A) OSI B) TCP/IP C) Both A and B D) Neither A nor B
A
20) Signals usually ________. A) spread over a range of frequencies B) travel at a single frequency
A
23) Channels with wide bandwidths are called ________ channels. A) broadband B) modulated C) multimode D) full-duplex
A
27) In the Shannon Equation, if you quadruple the bandwidth in a channel while the signal-to-noise ratio remains the same, you can transmit ________. A) about 4 times as fast B) at the same speed, but more reliably C) Log2(1+4) times as fast D) Log2(1+1/4) times as fast
A
3) Wireless LAN standards are created by the ________ Working Group. A) 802.11 B) 802.1 C) 802.3 D) 802.3W
A
31) In unlicensed bands, ________. A) you can use radios wherever you please B) you can prevent nearby businesses from setting up access points in the same channel C) Both A and B D) Neither A nor B
A
34) In 802.11, channel bandwidth usually is ________. A) 20 MHz B) 40 GHz C) 40 MHz D) 20 GHz
A
35) Which unlicensed band is defined the same way in most countries around the world? A) 2.4 GHz. B) 5 GHz. C) Both A and B D) Neither A nor B
A
39) Spread spectrum transmission is used in WLANs because ________. A) it is required by regulators B) it offers strong security C) Both A and B D) Neither A nor B
A
4) Wireless access points typically link wireless clients to ________. A) servers on the wired network B) wireless servers C) Both A and B
A
46) Access points take ________ from wireless devices and send them on to devices on the wired LAN. They also do the converse. A) packets B) frames C) Both A and B D) Neither A nor B
A
47) A wireless host sends a packet to a server on the company's wired Ethernet LAN via an access point. How many frames will be involved in this one-way transmission? A) 2 B) 1 C) 4 D) There will be one frame for each switch along the way.
A
5) Wireless radio transmission usually is expressed in terms of ________. A) frequency B) wavelength C) Both A and B D) Neither A nor B
A
61) When a wireless NIC wishes to transmit, it listens for traffic. If there is traffic, it waits. If there is no traffic, it may transmit. A) Sometimes true. B) False. C) True.
A
64) CSMA/CA+ACK is ________. A) inefficient B) efficient
A
68) Which of the following is more efficient? A) CSMA/CA+ACK. B) RTS/CTS. C) Both are about equally efficient.
A
7) The other wireless device is far away in a known direction. You should use ________. A) a dish antenna B) an omnidirectional antenna C) Both A and B D) Neither A nor B
A
77) Which of the following can operate in the 5 GHz band? A) 802.11ac B) 802.11g C) Both A and B D) Neither A nor B
A
79) In the 60 GHz service band, ________. A) channel bandwidth can be very wide B) signals travel farther C) Both A and B D) Neither A nor B
A
8) Cellular telephony uses ________. A) a dish antenna B) an omnidirectional antenna C) Both A and B D) Neither A nor B
A
88) If more users move to an access point, this decreases ________. A) individual throughput B) aggregate throughput C) Both A and B D) Neither A nor B
A
94) Mesh networking in 802.11 is likely to use ________. A) only wireless devices B) wireless devices and the site's wired LAN C) Both A and B
A
1) Wireless network standards operate at ________. A) the internet layer B) the data link layer C) Both A and B D) Neither A nor B
B
12) The most serious problem with wireless transmission in WLANs is ________. A) inverse square law attenuation B) multipath interference C) shadow zones D) absorptive attenuation
B
14) What propagation problem becomes worse as frequency increases? A) Electromagnetic interference. B) Absorptive attenuation. C) Both A and B D) Neither A nor B
B
36) Which unlicensed band provides greater propagation distance for a given level of power? A) 5 GHz. B) 2.4 GHz. C) Both A and B allow about the same propagation distance.
B
37) The 2.4 GHz band supports ________ nonoverlapping 20 MHz channel(s). A) 7 B) 3 C) 11 D) 1
B
38) The 5 GHz band supports about ________ nonoverlapping 20 MHz channel(s). A) 3 B) 12 C) 6 D) 1
B
40) Spread spectrum transmission is used in WLANs for ________. A) greater security B) more reliable transmission C) higher transmission speed D) All of the above
B
41) Spread spectrum transmission is used in commercial WLANs for security reasons.
B
44) When a WLAN is in use, the distribution system is the ________. A) radio transmitter in an access point B) Ethernet network C) radio transmitter in the access point controller D) collection of access points
B
54) In an extended service set, each access point ________. A) must have coordinated SSIDs B) must have the same SSID C) must have different SSIDs D) None of the above
B
56) What happens if two nearby access points use the same channel? A) They will be bonded for joint operation automatically. B) They will interfere with each other. C) They will be bonded for joint operation automatically if they use CSMA/CA+ACK. D) They will be bonded for joint operation automatically if they use RTS/CTS.
B
6) Frequency is measured in terms of ________. A) nanometers B) hertz C) Both A and B D) Neither A nor B
B
66) CSMA/CA+ACK usually is ________. A) optional B) required
B
67) Which of the following is usually optional in access point operation? A) CSMA/CA+ACK. B) RTS/CTS. C) Both A and B D) Neither A nor B
B
73) Which of the following brings gigabit speeds to clients? A) 802.11n B) 802.11ac C) 802.11g D) None of the above
B
15) What propagation problem becomes worse as frequency increases? A) Shadow zones. B) Absorptive attenuation. C) Both A and B D) Neither A nor B
C
17) The total range of possible 802.11 WLAN frequencies in the 2.4 GHz band constitutes ________. A) a frequency spectrum B) a broadband C) a service band D) a channel
C
19) To handle multiple conversations in radio transmission, you use multiple ________. A) service bands B) frequencies C) channels D) wires
C
24) To transmit data very rapidly, you would want a ________ channel. A) single-frequency band B) narrowband C) broadband D) Any of the above
C
26) In the Shannon Equation, C is the ________. A) actual speed of transmission in a channel B) minimum possible speed of transmission in a channel C) maximum possible speed of transmission in a channel D) channel bandwidth
C
28) The frequency range from 500 megahertz to 10 gigahertz is called the ________. A) frequency spectrum B) unlicensed band C) golden zone D) commercial mobile service band
C
33) 802.11 standards are being developed to work in the ________ unlicensed band. A) 5 GHz B) 2.4 GHz C) Both A and B D) Neither A nor B
C
43) Which of the following uses OFDM? A) 802.11n. B) 802.11g. C) Both A and B D) Neither A nor B
C
48) An access point and the set of hosts it serves is called a(n) ________. A) BSSID B) ESS C) BSS D) None of the above
C
49) The ________ is the identifier in a basic service set. A) BSSID B) BSS C) SSID
C
51) When a host moves from one wireless access point to another in a WLAN, this is ________. A) roaming B) a handoff C) Both A and B D) Neither A nor B
C
55) The standard for roaming among access points is ________. A) 802.11s B) 802.11W C) 802.11r D) None of the above
C
57) There is an access point that serves eight wireless hosts. On how many channels will these devices transmit during the course of an hour or two? A) 7 B) 8 C) 1 D) 2
C
58) ________ is a technique for preventing two wireless stations from transmitting at the same time and therefore interfering with each other. A) Roaming B) The distribution system C) Media access control D) Creating extended service sets
C
60) Media access control governs transmission by ________. A) access points B) wireless hosts C) Both A and B D) Neither A nor B
C
65) In ________, when a wireless host wishes to send, it first sends a message to the wireless access point asking for permission to send. When the access point sends back a response, the host sending the original message may transmit. All other hosts must wait. A) CSMA/CA B) CSMA/CA+ACK C) RTS/CTS D) CSMA/CD
C
71) For which standard is 300 Mbps a typical rated speed? A) 802.11ad. B) 802.11ac. C) 802.11n. D) 802.11g.
C
74) For wireless backup, which of the following is adequate? A) 802.11g B) 802.11n C) 802.11ac D) All of the above
C
75) Which of the following uses OFDM? A) 802.11ac B) 802.11g C) Both A and B D) Neither A nor B
C
78) In the 5 GHz band, how many channels can you have with 802.11ac with 80 GHz channels? A) 1 B) 12 C) 6 D) 24
C
80) MIMO ________. A) uses a single spatial stream but multiple signals B) bonds channels for higher speed C) transmits multiple signals in the same channel D) is used in all forms of 802.11
C
83) Beamforming can ________. A) direct signal strength at individual wireless hosts B) transmit multiple spatial data streams in the same channel C) Both A and B D) Neither A nor B
C
84) Beamforming can allow an access point to ________. A) send signals to two different clients at the same time B) direct power to individual clients C) Both A and B D) Neither A nor B
C
92) Using unused transmission channels in a service band is called using ________. A) dark spectrum B) opportunistic agility C) white space D) a smart antenna
C
13) What propagation problem becomes worse as frequency increases? A) Inverse square law attenuation. B) Electromagnetic interference. C) Both A and B D) Neither A nor B
D
16) The frequency spectrum extends ________. A) into the ultraviolet range B) into the gigahertz range C) into the visible light range D) to infinity
D
21) A channel extends from 55 MHz to 60 MHz. Its bandwidth is ________. A) 65 MHz B) 60 MHz C) 55 MHz D) None of the above
D
29) If a radio transmission is easily blocked by obstacles, then you need to maintain ________. A) deep transmission B) broadband transmission C) spread spectrum transmission interference D) a clear line of sight
D
42) A channel has more bandwidth than is necessary given data transmission speeds requirements in ________ transmission. A) licensed B) reliable commercial C) normal radio D) spread spectrum
D
50) To connect to an access point, you must know its ________. A) DSS B) BSS C) ESS D) None of the above
D
69) Which of the following is a full, according to the book? A) 802.11ac. B) 802.11ad. C) Both A and B D) Neither A nor B
D
70) Which of the following is a draft standard, according to the book? A) 802.11n. B) 802.11g. C) Both A and B D) Neither A nor B
D
72) For which of the following is 100 meters a typical service distance? A) 802.11n. B) 802.11g. C) Both A and B D) Neither A nor B
D
76) Wider channel bandwidth ________. A) allows more channels to be used in a service band B) decreases transmission speed C) Both A and B D) Neither A nor B
D
93) Two wireless devices communicate via Wi-Fi Direct using ________. A) an access point that lets them talk directly B) an Ethernet network to connect their access points C) Either A or B D) Neither A nor B
D
95) The 802.11 standard for mesh networking is ________. A) 802.11r B) 802.11m C) 802.11ac D) None of the above
D
18) The terms channel and service band mean roughly the same thing.
False
25) Networks that are fast are often called broadband whether or not they use radio channels.
False
45) Access points take frames from wireless devices and send these frames on to devices on the wired LAN.
False
59) An access point and a host it serves can transmit to each other simultaneously.
False
62) When a wireless NIC using CSMA/CD receives a frame correctly, it immediately sends back a reply without listening for traffic.
False
9) Radio has more reliable transmission than UTP.
False
96) Two WLAN products that conform to the same standard will have almost equal performance.
False
11) If the signal strength at 20 meters is 90 mW, the signal strength at 60 meters would be 10 mW.
True
52) In 802.11 WLANs, the terms handoff and roaming mean the same thing.
True
81) MIMO allows you to transmit two signals in the same channel.
True
86) Another name for beamforming is having a smart antenna.
True
89) As a station moves away from an access point, the access point transmits more slowly to it.
True
90) The presence of a client that is distant from the access point reduces the individual throughput of other clients served by that access point.
True
97) If a wireless client only has two MIMO antennas, an access point with three MIMO antennas will produce better performance than an access point with two MIMO antennas.
True
22) To transmit very rapidly in RADIO, you need ________. A) wide bandwidth B) narrow bandwidth C) single-frequency transmission D) single-mode transmission
A
30) WLANs normally use ________. A) unlicensed bands B) licensed bands
A
32) Interference is minimized in ________. A) licensed bands B) unlicensed bands
A
82) MIMO ________. A) increases throughput B) lowers propagation distance C) Both A and B D) Neither A nor B
A
85) Traditional MIMO can ________ A) send signals to two different clients at the same time B) send multiple signals in the same channel C) Both A and B D) Neither A nor B
B
91) If an 802.11n access point and an 802.11g client communicate, they communicate using ________. A) 802.11n B) 802.11g C) Either A or B D) Neither A nor B
B
53) An extended service set (ESS) is a group of BSSs that ________. A) have the same SSID B) are connected to the same distribution system C) Both A and B D) Neither A nor B
C
87) In 802.11 networks, the speed I receive on my portable devices is a(n) ________. A) individual throughput B) rated speed C) aggregate throughput D) None of the above
C
63) CSMA/CA+ACK is reliable.
True