Deck 7: Wireless Networks I

Question 1

The other wireless device is far away in a known direction.You should use ________.

A)an omnidirectional antenna
B)a dish antenna
C)Both A and B
D)Neither A nor B

Answer 1

B

Question 2

Wireless radio transmission usually is expressed in terms of ________.

A)wavelength
B)frequency
C)Both A and B
D)Neither A nor B

Answer 2

B

Question 3

Wireless LAN standards are created by the ________ Working Group.

A)802.1
B)802.3
C)802.11
D)802.3W

Answer 3

C

Question 4

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

Question 5

Wireless network standards operate at ________.

A)the data link layer
B)the internet layer
C)Both A and B
D)Neither A nor B

Question 6

Frequency is measured in terms of ________.

A)nanometers
B)hertz
C)Both A and B
D)Neither A nor B

Question 7

What propagation problem becomes worse as frequency increases?

A)Absorptive attenuation.
B)Electromagnetic interference.
C)Both A and B
D)Neither A nor B

Question 8

Wireless network standards come from ________.

A)OSI
B)TCP/IP
C)Both A and B
D)Neither A nor B

Question 9

Radio has more reliable transmission than UTP.

Question 10

The signal strength at 20 meters is 90 mW;the signal strength at 60 meters would be 10 mW.

Question 11

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 channel
D)a service band
E)All of the above.

Question 12

Cellular telephony uses ________.

A)an omnidirectional antenna
B)a dish antenna
C)Both A and B
D)Neither A nor B

Question 13

What propagation problem becomes worse as frequency increases?

A)Absorptive attenuation.
B)Shadow zones.
C)Both A and B
D)Neither A nor B

Question 14

The terms channel and service band mean roughly the same thing.

Question 15

Attenuation with distance is faster with ________.

A)UTP transmission
B)radio transmission
C)Both A and B
D)Neither A nor B

Question 16

A channel extends from 55 MHz to 60 MHz.Its bandwidth is ________.

A)60 MHz
B)55 MHz
C)65 MHz
D)None of the above.

Question 17

The most serious problem with wireless transmission in WLANs is ________.

A)inverse square law attenuation
B)absorptive attenuation
C)shadow zones
D)multipath interference

Question 18

Signals usually ________.

A)travel at a single frequency
B)spread over a range of frequencies

Question 19

To handle multiple conversations in radio transmission,you use multiple ________.

A)channels
B)frequencies
C)service bands
D)UWBs
E)wires

Question 20

The frequency spectrum extends ________.

A)into the megahertz range
B)into the gigahertz range
C)into the visible light range
D)into the ultraviolet range
E)to infinity

Question 21

In the Shannon Equation,C is the ________.

A)actual speed of transmission in a channel
B)maximum possible speed of transmission in a channel
C)minimum possible speed of transmission in a channel
D)channel bandwidth
E)signal-to-noise ratio

Question 22

Which unlicensed band provides greater propagation distance for a given level of power?

A)2.4 GHz.
B)5 GHz.
C)Both A and B allow about the same propagation distance.

Question 23

In 802.11,channel bandwidth usually is ________.

A)20 GHz
B)40 GHz
C)20 MHz
D)40 MHz

Question 24

If a radio transmission is easily blocked by obstacles,then you need to maintain ________.

A)a clear line of sight
B)spread spectrum transmission integrity
C)broadband transmission
D)deep transmission
E)shadow zone transmission

Question 25

802.11a supports ________ nonoverlapping channels.

A)1
B)3
C)7
D)More than 10

Question 26

What happens if two nearby access points use the same channel?

A)They will interfere with each other.
B)They will be bonded for joint operation automatically.
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.

Question 27

To transmit very rapidly in RADIO,you need ________.

A)single-frequency transmission
B)single-mode transmission
C)multimode transmission
D)wide bandwidth
E)narrow bandwidth

Question 28

WLANs normally use ________.

A)licensed bands
B)unlicensed bands

Question 29

The 2.4 GHz band supports ________ nonoverlapping channels.

A)1
B)3
C)7
D)11
E)more than 11

Question 30

Channels with wide bandwidths are called ________ channels.

A)single-mode
B)multimode
C)full-duplex
D)broadband
E)modulated

Question 31

The frequency range from 500 megahertz to 10 gigahertz is called the ________.

A)frequency spectrum
B)commercial mobile service band
C)UWB region
D)golden zone
E)unlicensed band

Question 32

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

Question 33

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

Question 34

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)None of the above.

Question 35

Spread spectrum transmission is used in WLANs for ________.

A)higher transmission speed
B)more reliable transmission
C)greater security
D)All of the above.

Question 36

802.11 standards are being developed to work in the ________ unlicensed band.

A)2.4 GHz
B)5 GHz
C)Both A and B
D)None of the above.

Question 37

What aspect of 802.11 standards affects interference between nearby access points?

A)The number of possible nonoverlapping channels.
B)The standard's minimum spacing parameter.
C)RTS/CTS.
D)All of the above.

Question 38

Interference is minimized in ________.

A)licensed bands
B)unlicensed bands

Question 39

To transmit data very rapidly,you would want a ________ channel.

A)narrowband
B)broadband
C)single-frequency band
D)Any of the above.

Question 40

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)Log2(1+4)times as fast
B)Log2(1+1/4)times as fast
C)about 4 times as fast
D)about 1/4 as fast
E)at the same speed,but more reliably

Question 41

(From the box,"Controlling 802.11 Transmission")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)True.
B)Sometimes true.
C)False.

Question 42

(From the box,"Controlling 802.11 Transmission")CSMA-CA+ACK is ________.

A)efficient
B)inefficient

Question 43

An access point and a host it serves can transmit to each other simultaneously.

Question 44

In 802.11 WLANs,the terms handoff and roaming mean the same thing.

Question 45

Which form of spread spectrum transmission divides the channel into many smaller channels called subcarriers?

A)DSSS.
B)FHSS.
C)OFDM.
D)All of the above.
E)None of the above.

Question 46

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)1.
B)2 (one in each direction).
C)7.
D)8.
E)9.

Question 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)1.
B)2.
C)3.
D)4.
E)There will be one frame for each switch along the way.

Question 48

Spread spectrum transmission is used in commercial WLANs for security reasons.

Question 49

Which of the following uses OFDM?

A)802.11g.
B)802.11n.
C)Both A and B
D)Neither A nor B

Question 50

(From the box,"Controlling 802.11 Transmission")CSMA-CA+ACK usually is ________.

A)required
B)optional

Question 51

(From the box,"Controlling 802.11 Transmission")When a wireless NIC receives a frame correctly,it immediately sends back a reply without listening for traffic.

Question 52

A channel has more bandwidth than is necessary given data transmission speeds requirements in ________ transmission.

A)normal radio
B)reliable commercial
C)spread spectrum transmission
D)licensed
E)None of the above.

Question 53

(From the box,"Controlling 802.11 Transmission")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+ACK
B)CSMA/CA
C)CSMA/CD
D)RTS/CTS

Question 54

Access points take ________ from wireless devices and send them on to devices on the wired LAN.They also do the converse.

A)frames
B)packets

Question 55

(From the box,"Controlling 802.11 Transmission")CSMA-CA+ACK is reliable.

Question 56

When a host moves from one wireless access point to another in a WLAN,this is ________.

A)a handoff
B)roaming
C)Both A and B
D)Neither A nor B

Question 57

(From the box,"Controlling 802.11 Transmission")Media access control governs transmission by ________.

A)access points
B)wireless NICs
C)Both A and B
D)Neither A nor B

Question 58

(From the box,"Controlling 802.11 Transmission")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

Question 59

Access points take frames from wireless devices and send these frames on to devices on the wired LAN.They also do the converse.

Question 60

Individual throughput falls as the number of wireless hosts using an access point increases.

Question 61

There is less interference in the 2.4 GHz band than in the 5 GHz band.

Question 62

802.11n will be superior to current 802.11 standards by ________.

A)offering wider channels
B)sending multiple spatial data streams in a single channel between wireless access points and wireless NICs
C)Both A and B
D)Neither A nor B

Question 63

The most widely used 802.11 LAN standard today is 802.11n.

Question 64

MIMO increases ________.

A)throughput
B)propagation distance
C)Both A and B
D)Neither A nor B

Question 65

Smart antennas 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

Question 66

802.11n may offer a rated speed of about ________.

A)11 Mbps
B)54 Mbps
C)300 Mbps
D)3 Gbps

Question 67

802.11g has a rated speed of ________.

A)11 Mbps
B)54 Gbps
C)300 Mbps
D)1 Gbps

Question 68

Which of the following is true?

A)An 802.11n host can work with an 802.11g access point.
B)An 802.11g host can work with an 802.11n access point.
C)Both A and B
D)Neither A nor B

Question 69

As a wireless host moves farther from a wireless access point,it is likely to transition to a slower modulation method.

Question 70

The most rapidly growing 802.11 LAN standard today is 802.11g.

Question 71

802.11n is designed to operate in the ________ unlicensed band.

A)2.4 GHz
B)5 GHz
C)Both A and B
D)Neither A nor B

Question 72

802.11n is faster than 802.11g because 802.11n ________

A)is designed to use wider channels
B)can send multiple signals (spatial transmission speeds)in a single channel
C)Both A and B
D)Neither A nor B

Question 73

An 802.11g access point has an actual speed of 30 MHz.This is ________.

A)the rated speed
B)aggregate throughput
C)channel bandwidth

Question 74

(From the box,"Controlling 802.11 Transmission")Which of the following is more efficient?

A)CSMA/CA+ACK.
B)RTS/CTS.
C)Both are about equally efficient.

Question 75

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

Question 76

Which of the following can offer speeds of about a gigabit per second?

A)802.11g.
B)802.11n.
C)802.11ac.
D)None of the above.

Question 77

802.11ad will ________.

A)operate in the 60 GHz radio band
B)have short propagation distance
C)Both A and B
D)Neither A nor B

Question 78

The most widely used 802.11 standard today is ________.

A)802.11a
B)802.11b
C)802.11e
D)802.11g
E)802.11n