Download True-False Questions

Chapter 8
Telecommunications, Networks, and Wireless Computing
8-1
Chapter 8
Telecommunications, Networks, and Wireless
Computing
True-False Questions
1.
When selecting appropriate technologies for enterprise networking, Internet technology,
XML, and Java allow for maximum connectivity and application integration.
Answer: False
2.
Reference: p. 268
Difficulty: Medium
Reference: p. 268
Difficulty: Medium
Reference: p. 268
Difficulty: Medium
Reference: p. 268
The X.25 packet switching standard uses packets of 128 bytes each.
Answer: True
9.
Difficulty: Medium
A data server is a specialized communications processor that forwards data from one
network to another network.
Answer: False
8.
Reference: p. 267
The Internet is based on peer-to-peer networking.
Answer: False
7.
Difficulty: Medium
Peer-to-peer networking has become the predominant model for corporate computing.
Answer: False
6.
Reference: p. 267
Message switching is a technology that breaks messages into small, fixed bundles of data
and routes them in the most economical way through any available communications channel.
Answer: False
5.
Difficulty: Medium
Public networking is the linking of separate networks, each of which retains its own identity,
into an interconnected network.
Answer: False
4.
Reference: p. 266
The use of packet switching to increase telecommunications transmission efficiency is one of
the three major developments that has shaped contemporary digital telecommunications
systems.
Answer: True
3.
Difficulty: Medium
Difficulty: Easy
Reference: p. 268
The OSI model is the dominant model for achieving connectivity among different networks,
providing an agreed-on method for breaking up digital messages into packets, routing them
to the proper addresses, and then reassembling them into coherent messages.
Answer: False
Difficulty: Medium
Reference: p. 269
8-2
Telecommunications, Networks, and Wireless Computing
10.
The PDA connectivity model is the one used in the Internet.
Answer: False
11.
Difficulty: Medium
Reference: p. 271
Difficulty: Medium
Reference: p. 272
Difficulty: Hard
Reference: p. 272
Difficulty: Easy
Reference: p. 273
Difficulty: Hard
Reference: p. 273
Difficulty: Medium
Reference: p. 274
Security is a problem for wireless transmission because it is easily intercepted.
Answer: True
22.
Reference: p. 271
Mobile data networks are not explicitly designed for two-way transmissions of data files.
Answer: False
21.
Difficulty: Easy
Personal communication services are entirely digital.
Answer: True
20.
Reference: p. 271
Today paging devices can transmit short alphanumeric messages.
Answer: True
19.
Difficulty: Easy
Infrared transmissions fall in a higher frequency range than microwave transmissions.
Answer: True
18.
Reference: p. 270
The electromagnetic spectrum is the wireless transmission medium.
Answer: True
17.
Difficulty: Easy
Presently, a problem with optical transmission is that it must convert data back and forth to
electrical signals.
Answer: True
16.
Reference: p. 270
Optical networks can transmit voice, data, and video.
Answer: True
15.
Difficulty: Medium
Until recently, fiber-optic cable was the least expensive medium for telecommunications.
Answer: False
14.
Reference: p. 269
A digital signal is a continuous waveform.
Answer: False
13.
Difficulty: Medium
If two computers are based on different hardware and software platforms, they will not be
able to communicate via TCP/IP.
Answer: False
12.
Chapter 8
Difficulty: Easy
Reference: p. 274
The bit rate is frequently smaller than the baud rate.
Answer: False
Difficulty: Hard
Reference: p. 274
Chapter 8
23.
Telecommunications, Networks, and Wireless Computing
Bandwidth is the highest frequency that the channel can accommodate.
Answer: False
24.
Reference: p. 281
Difficulty: Hard
Reference: p. 281
Difficulty: Easy
Reference: p. 281
Difficulty: Easy
Reference: p. 281
Difficulty: Medium
Reference: p. 281
Difficulty: Medium
Reference: p. 281
A T1 channel can be configured to carry either voice or data traffic.
Answer: True
34.
Difficulty: Medium
A T1 line is a dedicated telephone connection of 24 channels.
Answer: True
33.
Reference: p. 279
Presently, a cable modem has stronger capabilities for receiving data than for sending data.
Answer: True
32.
Difficulty: Easy
ADSL supports a transmission rate of 1.5 to 9 megabits per second when receiving data.
Answer: True
31.
Reference: p. 279
A digital subscriber line can operate over existing copper telephone lines and has a higher
transmission capacity than ISDN.
Answer: True
30.
Difficulty: Hard
Basic rate ISDN can transmit data at a rate of 512 kilobits per second on an existing local
telephone line.
Answer: False
29.
Reference: p. 276
ATM parcels information into 8-byte cells, allowing data to be transmitted between computers
from different vendors at high speeds.
Answer: True
28.
Difficulty: Easy
When using a value-added network, subscribers pay only for the amount of data they
transmit plus a subscription fee.
Answer: True
27.
Reference: p. 274
Switched lines are continuously available for transmission because they have been changed
from voice lines to data lines.
Answer: False
26.
Difficulty: Medium
Ring and bus topologies are used in LANs.
Answer: True
25.
8-3
Difficulty: Easy
Reference: p. 281
Cable modems provide high-speed transmission over cable TV lines and are shared by
many users.
Answer: True
Difficulty: Easy
Reference: p. 281
8-4
Telecommunications, Networks, and Wireless Computing
35.
A broadband medium can transmit multiple channels of data simultaneously.
Answer: True
36.
Reference: p. 282
Difficulty: Easy
Reference: p. 284
Difficulty: Medium
Reference: p. 285
EDI allows computer-to-computer exchange of standardized documents between two
organizations and lowers transaction costs.
Answer: True
40.
Difficulty: Easy
Digital learning refers to instruction delivered through purely digital technology, such as CDROMs, the Internet, or private networks.
Answer: False
39.
Reference: p. 281
The ability of two or more people at distant locations to edit and modify the same document
simultaneously is called teleconferencing.
Answer: False
38.
Difficulty: Medium
Communications companies and commercial on-line services offer electronic mail to their
users.
Answer: True
37.
Chapter 8
Difficulty: Easy
Reference: p. 286
EDI differs from e-mail in that it transmits an actual structured transaction as opposed to an
unstructured text message such as a letter.
Answer: True
Difficulty: Medium
Reference: p. 286
Multiple- Choice Questions
41.
A collection of compatible hardware and software arranged to communication information
from one location to another best describes:
a.
b.
c.
d.
e.
telecommunication system.
legacy system.
corporate system.
communication system.
network operating system.
Answer: a
Difficulty: Medium
Reference: p. 266
Chapter 8
42.
Telecommunications, Networks, and Wireless Computing
Various networks that are linked together to make information flow freely throughout
different parts of the organization and between the organization and its external
environment best describes:
a.
b.
c.
d.
e.
internetworking.
enterprise networking.
cooperative networking.
extranet.
virtual private networking.
Answer: b
43.
Difficulty: Medium
Reference: p. 268
Which of the following is the connectivity model used in the Internet?
a.
b.
c.
d.
e.
ISDN
DWDM
GSM
TCP/IP
OSI
Answer: d
Difficulty: Medium
Reference: p. 269
Which of the following is not one of the TCP/IP layers?
a.
b.
c.
d.
e.
Application layer
Presentation layer
Transportation layer
Internet layer
Network interface layer
Answer: b
46.
Reference: p. 267
ISDN
Dense wavelength division multiplexing
Packet switching
Time division multiplexing
TDMA
Answer: c
45.
Difficulty: Medium
Which of the following is a technology that breaks messages into small, fixed bundles of
data and routes them in the most economical way through any available communications
channel?
a.
b.
c.
d.
e.
44.
8-5
Difficulty: Hard
Reference: p. 269
“Crosstalk” is:
a.
b.
c.
d.
e.
two data communications on the same fiber-optic cable.
two computers of different architecture talking to each other.
interference with the signals on twisted wire media during high-speed transmission.
set up by protocols.
changing an analog signal to a digital one.
Answer: c
Difficulty: Medium
Reference: p. 270
8-6
Telecommunications, Networks, and Wireless Computing
47.
Optical networks transmit:
a.
b.
c.
d.
e.
voice.
data
video.
using pulses of light.
All of the above
Answer: e
48.
Difficulty: Easy
Reference: p. 271
The part of a network that handles major traffic and provides the primary path for traffic
flowing to or from other networks best describes:
a.
b.
c.
d.
e.
bus.
switch.
backbone.
server.
node.
Answer: c
Difficulty: Medium
Reference: p. 271
The ability of a single communications channel to carry data transmissions from multiple
sources simultaneously best defines:
a.
b.
c.
d.
e.
packet switching.
circuit switching.
parallel processing.
multiplexing.
baseband.
Answer: d
51.
Reference: p. 271
strands of clear glass fibers.
glass fibers wound with copper wire.
twisted pairs of glass fibers.
dedicated 10-megabit lines.
glass fibers transmitting an analog signal.
Answer: a
50.
Difficulty: Easy
Fiber-optic cable consists of:
a.
b.
c.
d.
e.
49.
Chapter 8
Difficulty: Medium
Reference: p. 271
Technology for boosting transmission capacity of optical fiber by using many different
wavelengths to carry separate streams of data over the same fiber strand at the same
time best describes:
a.
b.
c.
d.
e.
optical division multiplexing.
dense wavelength division multiplexing.
digital streamlined multiplexing.
broadband multiplexing.
Wi-Fi.
Answer: b
Difficulty: Hard
Reference: p. 271
Chapter 8
52.
Telecommunications, Networks, and Wireless Computing
8-7
DWDM uses:
a. infrared data transmission.
b. satellite transmissions.
c. different colors of light to carry different messages over the same strand at the same
time.
d. differently-timed pulses of light to carry different messages over the same strand at
the same time.
e. a single wavelength per strand.
Answer: c
53.
microwave transmission.
communication satellites.
pagers.
personal communication services.
All of the above
Answer: e
Reference: p. 272
follow a straight line.
require the transmission stations be positioned 37 miles apart.
do not bend with the curvature of the earth.
are widely used for high-volume, long-distance, point-to-point communication.
All of the above
Answer: d
Difficulty: Easy
Reference: p. 272
Communications satellites are:
a.
b.
c.
d.
e.
relay stations for fiber-optic transmissions.
outside the electromagnetic spectrum.
used mainly by cell phones.
usually in very high orbits so they will not interfere with space stations.
cost effective for transmitting large quantities of data over very long distances.
Answer: e
56.
Difficulty: Easy
Microwave signals:
a.
b.
c.
d.
e.
55.
Reference: p. 271
Common technologies for wireless data transmission include:
a.
b.
c.
d.
e.
54.
Difficulty: Hard
Difficulty: Medium
Reference: p. 272
In ascending order, the frequency ranges for communications media are:
a.
b.
c.
d.
e.
radio, infrared, ultraviolet, visible light, X-ray, and gamma/cosmic.
X-ray, infrared, ultraviolet, microwave, visible light, and gamma/cosmic.
radio, microwave, infrared, visible light, ultraviolet light, X-ray, and gamma/cosmic.
gamma/cosmic, X-ray, visible light, ultraviolet, microwave, infrared, and radio.
radio, microwave, infrared, ultraviolet, visible light, X-ray, and gamma/cosmic.
Answer: c
Difficulty: Hard
Reference: p. 272
8-8
Telecommunications, Networks, and Wireless Computing
57.
A wireless cellular technology that uses lower-power, higher-frequency radio waves than
does cellular technology best defines:
a.
b.
c.
d.
e.
personal digital assistants.
packet distribution networks.
paging system.
personal communications services.
mobile data networks.
Answer: d
58.
Difficulty: Easy
Reference: p. 273
In a cell-phone network, each radio antenna cell normally covers:
a.
b.
c.
d.
e.
a 30-mile area, overlapping with adjacent cells by about 5 miles.
radio and microwave transmissions, but not digital transmission.
only phones of the particular cell-phone service being used.
an eight-mile hexagonal cell.
line-of-sight to any other antenna.
Answer: d
Difficulty: Medium
Reference: p. 273
PDAs:
a.
b.
c.
d.
e.
have built-in wireless telecommunications capabilities.
are small, pen-based, handheld computers.
are capable of entirely digital transmission.
have work-organization software.
All of the above
Answer: e
61.
Reference: p. 273
send and receive short alphanumeric messages.
send only analog signals.
send only digital signals.
be used over long distances with special microwave transmitters.
support groupware applications.
Answer: a
60.
Difficulty: Medium
Paging devices today can:
a.
b.
c.
d.
e.
59.
Chapter 8
Difficulty: Easy
Reference: p. 273
Because wireless transmission can be easily intercepted:
a.
b.
c.
d.
e.
it is not useful in digital environments.
security and privacy are more difficult.
it is best used for cable television.
even a radio can pick up the digital signal.
Both a and c
Answer: b
Difficulty: Easy
Reference: p. 274
Chapter 8
62.
Telecommunications, Networks, and Wireless Computing
Data can be transmitted seamlessly between different wireless networks:
a.
b.
c.
d.
e.
only over short distances.
only if they use compatible standards.
only over the Internet.
only with government permission.
only when cellular phones are used.
Answer: b
63.
Difficulty: Medium
Reference: p. 274
A change in signal from positive to negative or vice versa that is used as a measure of
transmission speed best defines:
a.
b.
c.
d.
e.
baud.
bits per second.
multiplex.
digital differential.
transmission rate.
Answer: a
Difficulty: Medium
Reference: p. 274
At its fastest, fiber-optic cable can transmit data at speeds of:
a.
b.
c.
d.
e.
1.544 megabits per second.
1024 bits per second.
up to 2.56 megabits per second.
up to 6 terabits per second.
1 terabit per second.
Answer: d
66.
Reference: p. 274
can transmit several messages at once.
can transmit microwave frequencies.
can be measured only in hertz.
can transmit more than one bit at a time.
can decrease the baud rate.
Answer: d
65.
Difficulty: Hard
At higher speeds, a single signal change:
a.
b.
c.
d.
e.
64.
8-9
Difficulty: Medium
Reference: p. 275
A star network is a:
a. network topology in which all computers and other devices are connected to a central
hub.
b. network topology in which all computers are linked by a closed loop in a manner that
passes data in one direction from one computer to another.
c. network topology linking a number of computers by a single circuit with all messages
broadcast to the entire network.
d. network architecture that gives equal power to all computers on the network.
e. telecommunications network that spans a large geographical distance.
Answer: a
Difficulty: Medium
Reference: p. 276
8-10
Telecommunications, Networks, and Wireless Computing
67.
Chapter 8
A ring network is a:
a. network topology in which all computers and other devices are connected to a central
hub.
b. network topology in which all computers are linked by a closed loop in a manner that
passes data in one direction from one computer to another.
c. network topology linking a number of computers by a single circuit with all messages
broadcast to the entire network.
d. network architecture that gives equal power to all computers on the network.
e. telecommunications network that spans a large geographical distance.
Answer: b
68.
Difficulty: Medium
Reference: p. 276
Peer-to-peer is a:
a. network topology in which all computers and other devices are connected to a central
hub.
b. network topology in which all computers are linked by a closed loop in a manner that
passes data in one direction from one computer to another.
c. network topology linking a number of computers by a single circuit with all messages
broadcast to the entire network.
d. network architecture that gives equal power to all computers on the network.
e. telecommunications network that spans a large geographical distance.
Answer: d
69.
Difficulty: Medium
Reference: p. 276
A bus network is a:
a. network topology in which all computers and other devices are connected to a central
hub.
b. network topology in which all computers are linked by a closed loop in a manner that
passes data in one direction from one computer to another.
c. network topology linking a number of computers by a single circuit with all messages
broadcast to the entire network.
d. network architecture that gives equal power to all computers on the network.
e. telecommunications network that spans a large geographical distance.
Answer: c
70.
Difficulty: Medium
Reference: p. 276
The LAN network interface card:
a.
b.
c.
d.
e.
specifies the data transmission rate.
specifies the size of the message units.
specifies the addressing information attached to each message.
specifies the network topology.
All of the above
Answer: e
Difficulty: Easy
Reference: p. 276
Chapter 8
71.
Telecommunications, Networks, and Wireless Computing
Which of the following is the Wi-Fi mode where wireless devices communicate with a
wired LAN via access points?
a.
b.
c.
d.
e.
Peer mode
Ad-hoc mode
Star mode
Infrastructure mode
Multiplexed mode
Answer: d
72.
Difficulty: Hard
Reference: p. 277
Which of the following is a specific geographic location in which an access point provides
public Wi-Fi network service?
a.
b.
c.
d.
e.
Connect point
Peer point
Hot spot
Node location
Wi-Fi channel
Answer: c
Difficulty: Medium
Reference: p. 278
A private, multipath, data-only, third-party-managed network that multiple organizations
use on a subscription basis best describes:
a.
b.
c.
d.
e.
local area network.
peer-to-peer network.
Wi-Fi network.
wide area network.
value-added network.
Answer: e
75.
Reference: p. 277
Peer mode
Ad-hoc mode
Star mode
Infrastructure mode
Multiplexed mode
Answer: b
74.
Difficulty: Hard
Which of the following is the Wi-Fi mode where wireless devices communicate with each
other directly and do not use an access point?
a.
b.
c.
d.
e.
73.
8-11
Difficulty: Medium
Reference: p. 279
A networking technology that parcels information into 8-byte cells, allowing data to be
transmitted between computers from different vendors at high speeds best describes:
a.
b.
c.
d.
e.
broadband.
asynchronous transfer mode.
integrated services digital network.
converged network.
star network.
Answer: b
Difficulty: Medium
Reference: p. 281
8-12
Telecommunications, Networks, and Wireless Computing
76.
Primary Rate ISDN:
a.
b.
c.
d.
e.
parcels information into 8-byte cells.
requires a fiber-optic line.
operates over cable TV lines as well as telephone lines.
is used for high-capacity Internet connections.
offers transmission capacities in the megabit range.
Answer: e
77.
Chapter 8
Difficulty: Hard
Reference: p. 281
Broadband:
a. works only for cable TV connections.
b. designates a communications medium that can transmit multiple channels of data
simultaneously.
c. enables voice and data to run on a single network.
d. is for high-frequency transmissions.
e. does not maintain separate networks for voice and data.
Answer: b
78.
Difficulty: Easy
Reference: p. 281
A voice mail system:
a. is necessary for groupware to work efficiently.
b. allows data conferencing.
c. digitizes the sender’s spoken message, transmits it over a network, and stores it for
later retrieval.
d. allows simultaneous conference via telephone.
e. All of the above.
Answer: c
79.
Reference: p. 283
Electronic conferencing is growing in popularity because:
a.
b.
c.
d.
e.
travel time and costs are saved.
special software is not required.
any T1 line can use it.
employees can be monitored more closely.
of all of the above.
Answer: a
80.
Difficulty: Easy
Difficulty: Easy
Reference: p. 284
“E-learning” is the term used to describe:
a.
b.
c.
d.
e.
training in network technologies.
surfing the Internet.
training delivered over a distance.
on-line instruction delivered over the Internet or private networks.
what companies are finding out about new technologies.
Answer: d
Difficulty: Medium
Reference: p. 285
Chapter 8
Telecommunications, Networks, and Wireless Computing
8-13
Fill In the Blanks
81.
A(n) telecommunications system is a collection of compatible hardware and software
arranged to communicate information from one location to another.
Difficulty: Easy
82.
A(n) router is a specialized communications processor that forwards data packets from one
network to another network.
Difficulty: Medium
83.
Reference: p. 270
A(n) twisted wire is a transmission medium consisting of pairs of copper wires.
Difficulty: Easy
90.
Reference: p. 270
A(n) channel is the link by which data or voice is transmitted between sending and receiving
devices in a network.
Difficulty: Medium
89.
Reference: p. 270
A(n) modem is a device for translating a computer’s digital signals into analog form for
transmission over ordinary telephone lines, or for translating analog signals back into digital
form for reception by a computer.
Difficulty: Easy
88.
Reference: p. 270
A(n) digital signal is a discrete waveform that transmits data coded into two discrete states
as 1-bits and 0-bits, which are represented as on-off electrical pulses.
Difficulty: Easy
87.
Reference: p. 269
A(n) analog signal is a continuous waveform that passes through a communications
medium.
Difficulty: Medium
86.
Reference: p. 268
A(n) protocol is a set of rules and procedures that govern transmission between the
components in a network.
Difficulty: Medium
85.
Reference: p. 268
Packet switching is technology that breaks messages into small, fixed bundles of data and
routes them in the most economical way through any available communications channel.
Difficulty: Easy
84.
Reference: p. 266
Reference: p. 270
A(n) coaxial cable is a transmission medium consisting of thickly insulated copper wire that
can transmit large volumes of data quickly.
Difficulty: Easy
Reference: p. 271
8-14
Telecommunications, Networks, and Wireless Computing
91.
A(n) fiber-optic cable is a fast, light, and durable transmission medium consisting of thin
strands of clear glass fiber bound into cables.
Difficulty: Easy
92.
Reference: p. 273
A(n) cellular telephone is a device that transmits voice or data using radio waves to
communicate with radio antennas placed within adjacent geographic areas.
Difficulty: Easy
99.
Reference: p. 272
A(n) paging system is a wireless transmission technology in which the receiver beeps when
the user receives a message; it is used to transmit short alphanumeric messages.
Difficulty: Easy
98.
Reference: p. 272
Satellite transmission of data uses orbiting satellites that serve as relay stations for
transmitting microwave signals over very long distances.
Difficulty: Easy
97.
Reference: p. 271
Microwave is a high-volume, long-distance point-to-point transmission in which highfrequency radio signals are transmitted through the atmosphere from one terrestrial
transmission station to another.
Difficulty: Medium
96.
Reference: p. 271
Dense wave division multiplexing is a technology for boosting transmission capacity of
optical fiber by using many different wavelengths to carry separate streams of data over the
same fiber strand at the same time.
Difficulty: Hard
95.
Reference: p. 271
A(n) optical network is high-speed networking technology for transmitting data in the form of
light pulses.
Difficulty: Medium
94.
Reference: p. 271
A(n) backbone is the part of a network that handles the major traffic and provides the
primary path for traffic flowing to or from other networks.
Difficulty: Medium
93.
Chapter 8
Reference: p. 273
Personal communication services use a wireless cellular technology that uses lower
power, higher-frequency radio waves than does cellular technology.
Difficulty: Medium
Reference: p. 273
100. A(n) personal digital assistant is a small, pen-based, hand-held computer with built-in
wireless telecommunications capable of entirely digital communications transmission.
Difficulty: Medium
Reference: p. 273
101. A(n) smart phone is a wireless phone with voice, text, and Internet capabilities.
Difficulty: Easy
Reference: p. 274
Chapter 8
Telecommunications, Networks, and Wireless Computing
8-15
102. A(n) mobile data network is a wireless network that enables two-way transmission of data
files cheaply and efficiently.
Difficulty: Medium
Reference: p. 274
103. Baud is a change in signal from positive to negative or vice versa that is used as a measure
of transmission speed.
Difficulty: Medium
Reference: p. 274
104. Bandwidth is the capacity of a communications channel as measured by the difference
between the highest and lowest frequencies that can be transmitted by that channel.
Difficulty: Medium
Reference: p. 274
105. A(n) local area network requires its own dedicated channels and encompasses a limited
distance, usually one building or several buildings in proximity.
Difficulty: Medium
Reference: p. 275
106. Topology is the way in which the components of a network are connected.
Difficulty: Easy
Reference: p. 276
107. A(n) bus network has a number of computers linked by a single circuit with all messages
broadcast to the entire network.
Difficulty: Medium
Reference: p. 276
108. A(n) ring network has a number of computers linked by a closed loop in a manner that
passes data in one direction from one computer to another.
Difficulty: Medium
Reference: p. 276
109. A(n) network operating system is special software that routes and manages
communications on the network and coordinates network resources.
Difficulty: Easy
Reference: p. 276
110. A(n) peer-to-peer network architecture gives equal power to all computers on the network.
Difficulty: Easy
Reference: p. 276
111. A(n) wide area network is a network that spans a large geographical distance.
Difficulty: Easy
Reference: p. 279
112. A(n) dedicated line is a phone line that is continuously available for transmission by a
lessee.
Difficulty: Easy
Reference: p. 279
8-16
Telecommunications, Networks, and Wireless Computing
Chapter 8
113. A(n) value-added network is a private, multipath, data-only, third-party-managed network
that multiple organizations use on a subscription basis.
Difficulty: Medium
Reference: p. 279
114. A(n) frame relay is a shared network service technology that packages data into bundles for
transmission but does not use extensive error-correction routines.
Difficulty: Medium
Reference: p. 281
115. Asynchronous transfer mode is a networking technology that parcels information into 8byte cells, allowing data to be transmitted between computers from different vendors at high
speeds.
Difficulty: Medium
Reference: p. 281
116. Integrated Services Digital Network is an international standard for transmitting voice,
video, image, and data to support a wide range of service over the public telephone lines.
Difficulty: Hard
Reference: p. 281
117. Digital subscriber line refers to a group of technologies providing high-capacity
transmission over existing copper telephone lines.
Difficulty: Medium
Reference: p. 281
118. A(n) T1 line is a dedicated telephone connection comprising 24 channels that can support a
data transmission rate of 1.544 megabits per second.
Difficulty: Easy
Reference: p. 281
119. Broadband is a high-speed transmission technology; it also designates a single
communications medium that can transmit multiple channels of data simultaneously.
Difficulty: Medium
Reference: p. 281
120. A(n) converged network is a network with technology to enable voice, video, and data to
run over a single network.
Difficulty: Medium
Reference: p. 281
Chapter 8
Telecommunications, Networks, and Wireless Computing
8-17
Essay Questions
121.
Briefly describe the three major developments that have shaped contemporary digital
telecommunications systems.
The textbook mentions client/server computing, packet switching, and TCP/IP as the three
major developments. Client/server computing is a model of computing that divides the
processing between client computers and servers on a network. The tasks are assigned to
the machine most able to perform the tasks. Packet switching breaks messages into small,
fixed bundles of data and routes them in the most economical way through any available
communications channel. Packet switching enables packets to be transmitted independently
through various communications channels. TCP/IP is the connectivity model of the Internet,
providing a universally agreed-on method for breaking up digital messages into packets,
routing them to the proper addresses, and then reassembling them into coherent messages.
122.
List and describe the three major LAN topologies. What are the advantages and
disadvantages of each?
Star, bus, and ring are the three major LAN topologies. The star topology consists of a
central host computer connected to a number of smaller computers or terminals. It is useful
for applications where some processing must be centralized and some can be performed
locally. All communications between points in the network must pass through the central
computer. One problem with this topology is that everyone in the network goes down if the
central computer fails for any reason. The bus topology links a number of computers by a
single circuit made of twisted wire, coaxial cable, or fiber-optic cable. All signals are
broadcast in both directions to the entire network, with special software to identify which
components receive each message. There is no central computer controlling the network. If
one of the computers fails, none of the others are affected, and work can continue.
However, since the channel can handle only one message at a time, performance can
degrade if there is a high volume of network traffic. The ring topology like the bus network
does not rely on a central host and will not necessarily break down if one of the component
computers malfunctions. Each computer in the network can communicate directly with any
other computer, and each processes its own applications independently. However, in a ring
topology, the connecting wire forms a closed loop, and all data flows in one direction around
the loop.
123.
What is TCP/IP? Identify its layers.
TCP/IP is the connectivity model used by the Internet; it provides a universally agreed-on
method for breaking up digital messages into packets, routing them to the proper addresses,
and then reassembling them into coherent messages. The TCP/IP layers are application,
transport, internet, and network interface.
124.
Distinguish between an analog signal and a digital signal.
An analog signal is a continuous waveform passing through a communications medium.
Analog signals handle voice communications and reflect variations in pitch. A digital signal is
a discrete, rather than a continuous waveform, using only two states, 1-bits and 0-bits
representing either/or conditions or on-off electrical pulses.
Standard telephone lines speak analog; computers speak digital. To communicate, the
digital signal either 1) must be changed to an analog signal as it travels the medium, then
changed back to a digital signal for the computer at the other end, or 2) sent in digital pulses
over a medium that is also digital.
8-18
Telecommunications, Networks, and Wireless Computing
125.
Chapter 8
List and describe the three forms of wired transmission used in the
telecommunications industry, and give one advantage and one disadvantage for each.
Twisted wire refers to strands of copper wire twisted in pairs. Most standard telephone lines
are twisted pairs and have been for many years. Twisted pairs can be used for digital
transmission as well as analog. Its main advantages are low cost and it is already in place.
Disadvantages include relatively slow for transmitting data, and the problem of “crosstalk” in
which the signal “bleeds” from one wire to another during high-speed transmission. Coaxial
cable is thickly insulated copper wire, which can transmit a larger volume of data than twisted
wire. Advantages include its speed and having less interference. Disadvantages include the
cable is thick and heavy, and it is hard to install in many buildings. Also, it cannot support
analog phone conversations. Fiber-optic cable consists of thousands of very thin strands of
clear glass fiber, bound into a cable. Data are transmitted over each strand by pulses of
light, which are sent by laser at very high speed. Fiber optic advantages include faster,
lighter, more durable, and the ability to transfer large volumes of data quickly. Its
disadvantages are that it is difficult to work with, expensive, and harder to install.
126.
Define “wireless transmission” and list at least two advantages and two
disadvantages to its use.
Wireless transmission sends signals (using the electromagnetic spectrum) through air or
space without any physical tether. Common technologies for wireless transmission include
microwave transmission, communication satellites, pagers, cell phones, personal
communication services, smart phones, personal digital assistants, and mobile data
networks. Advantages include no limitation on where communications may take place, since
the signal can be bounced off satellites to line-of-sight towers and no limitation of the
movement of the persons communicating, because no wires are involved. Disadvantages
include being more expensive, slower, and more error prone than wired networks. Security
and privacy are difficult because wireless transmissions are easily intercepted. Different
wireless networks cannot transmit data seamlessly if they use incompatible standards or
different frequencies.
127.
Briefly discuss Wi-Fi.
Wi-Fi is the emerging standard for wireless LANs. The 802.a standard transmits up to 54
Mbps in the unlicensed 5-Ghz frequency range and has an effective distance up to 30
meters. The 802.11b standard transmits up to 11 Mbps in the unlicensed 2.4 GHz band and
has an effective distance up to 50 meters. The 802.11g standard transmits up to 54 Mbps in
the 2.4 GHz range. Wi-Fi systems can operate either in infrastructure or ad-hoc mode.
When operating in infrastructure mode, wireless devices communicate with a LAN through
access points. In ad-hoc mode, wireless devices communicate directly and do not use
access points.
Chapter 8
128.
Telecommunications, Networks, and Wireless Computing
8-19
What are at least five considerations management must examine to establish the
telecommunications needs of a company?
Management should consider the following:
1. Distance—are the needs of the company local or long-distance?
2. Services—what range of services will be needed (e-mail, EDI, voice mail,
videoconferencing, graphics transmission)? Do they need to be integrated?
3. Points of access—how many different locations and users in the organization require
access to the communications services and capabilities?
4. Utilization—what frequency and volume of communications does your firm anticipate?
5. Cost—how much can you spend and on what?
6. Security—what level of security and reliability must be maintained?
7. Connectivity—how much time, money, and effort will be required to make sure all the
components of the network or multiple networks can communicate with each other?
129.
Distinguish between EDI and ATM.
ATM is “asynchronous transfer mode” and is capable of seamlessly switching voice, data,
images, and video between users using computers from different vendors. EDI is the
computer-to-computer exchange between two organizations of standard transaction
documents such as invoices, bills of lading, and purchase orders.
130.
Distinguish between the two types of ISDN services and the two types of DSL
services.
ISDN—stands for Integrated Services Digital Network, and is an international standard for
dial-up network access that integrates voice, data, image, and video services in a single link.
Basic rate ISDN can transmit data at a rate of 128 kilobits per second on an existing local
telephone line. Primary rate ISDN offers transmission capacities in the megabit range and is
designed for large users of telecommunications services.
DSL—stands for Digital Subscriber Line, and also carry e-mail, data, image, and video
services in a single link over regular copper phone lines, but they have higher transmission
capacities than ISDN. ADSL (asymmetric digital subscriber line) supports 1.5 to 9 megabits
per second when receiving data and up to 640 kilobits per second when sending data. SDSL
(symmetric digital subscriber line) supports the same transmission rate and can receive data
at up to 3 megabits per second.