Chapter 6 Test 2

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A cellular telephone uses a(n) ________. A) omnidirectional antenna

A

A single access point and the set of hosts it serves is called a(n) ________. A) BSS

A

CSMA/CA+ACK usually is ________. A) mandatory

A

Companies are moving to the 5 GHz band because there is ________ than in the 2.5 GHz band. A) more bandwidth

A

Compared to wired transmission, propagation problems in radio transmission are ________. A) worse

A

In an extended service set, each access point ________. A) must have the same SSID

A

In unlicensed bands, ________. A) you can use radios wherever you please

A

MIMO ________. A) increases throughput

A

Spread spectrum transmission is used in WLANs because ________. A) it is required by regulators

A

The standard for roaming among access points is ________. A) 802.11r

A

There is an access point that serves eight wireless hosts. On how many channels will these devices transmit and receive during the course of an hour or two? A) 1

A

To connect to an access point, you must know its ________. A) SSID

A

To handle multiple conversations in radio transmission, you normally use multiple ________. A) channels

A

To use an access point, you need to know its ________. A) SSID

A

What happens if two nearby access points use the same channel? A) They will interfere with each other.

A

What propagation problem is especially bad in moist air? A) absorptive attenuation

A

Which of the following is more efficient and faster? A) CSMA/CA+ACK

A

Which of the following is the newest Wi-Fi standard? A) 802.11ac

A

Wider channel bandwidth ________. A) increases transmission speed

A

Wireless network standards are ________ standards. A) OSI

A

Wireless network standards operate at ________. A) the data link layer

A

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? B) 2

B

Access points in the same ESS communicate via ________. B) the distribution system

B

CSMA/CD+ACK is ________. B) reliable

B

Frequency is measured in terms of ________. B) hertz

B

In the 5 GHz band, how many channels can you have with 802.11ac with 80 GHz channels? B) 6

B

Signals in a transmission usually ________. B) spread over a range of frequencies

B

Spread spectrum transmission is used in WLANs for ________. B) more reliable transmission

B

The 2.4 GHz band supports ________ possible non-overlapping 20 MHz channel(s). B) 3

B

The 802.11 standard has two mechanisms for media access control. One of two mechanisms is mandatoryit is ________. B) CSMA/CA+ACK

B

The other wireless device is far away in a known direction. It would be better to use ________. B) a dish antenna

B

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

B

WLANs normally use ________. B) unlicensed bands

B

What propagation problem becomes worse as there is a large and dense object between sender and receiver? B) shadow zones or dead zones

B

Which of the following only operates in the 5 GHz band? B) 802.11ac

B

Wireless access points typically link wireless clients to ________. B) servers on the wired network

B

Wireless radio transmission speed is usually measured in terms of ________. B) frequency

B

________ have SSIDs. B) Wireless access points

B

802.11 standards are being developed to work in the ________ unlicensed band. A) 2.4 GHz B) 5 GHz C) both A and B

C

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

C

An extended service set (ESS) is a group of BSSs that ________. A) are connected to the same distribution system B) have the same SSID C) both A and B

C

Beamforming can allow an access point to ________. A) direct power to individual clients B) send signals to two different clients at the same time C) both A and B

C

Channels with wide bandwidths are called ________ channels. C) broadband

C

In 802.11g, channel bandwidth usually is ________. C) 20 MHz

C

In CSMA/CD+ACK, when a wireless NIC wishes to transmit, it listens for traffic. If there is traffic, it waits. When the traffic stops, it may transmit immediately. C) always false

C

Media access control governs transmission by ________. A) access points B) wireless hosts C) both A and B

C

Radio transmission is measured in terms of ________. C) frequency

C

To transmit very rapidly in RADIO, you need ________. C) wide bandwidth

C

We use the terms Wi-Fi and ________ interchangeably in this book. C) 802.11

C

Which of the following uses OFDM? A) 802.11ac B) 802.11n C) both A and B

C

Wi-Fi Standards come from the ________ Working Group. C) 802.11

C

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

D

At 10 meters, a signal has a strength of 100 mW. About how strong will it be at 40 meters? D) about 6 mW

D

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. D) RTS/CTS

D

MIMO ________. D) transmits multiple signals in the same channel

D

The 5 GHz band usually supports about ________ non-overlapping 20 MHz channel(s). D) 12

D

The frequency spectrum extends ________. D) to infinity

D

The most serious problem with wireless transmission in WLANs is ________. D) multipath interference

D

Today, Wi-Fi sales are dominated by ________. D) 802.11ac

D

What propagation problem becomes worse as frequency increases? D) neither A nor B

D

________ is a technique for preventing two wireless stations from transmitting at the same time and therefore interfering with each other. D) Media access control

D

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

A

2.4 GHz and 5 GHz are ________. D) service bands

D


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