Network+ Guide to Networks 6th Edition by Tamara Dean – Test Bank

Network+ Guide to Networks 6th Edition by Tamara Dean – Test Bank

Chapter 7:Wide Area Networks

TRUE/FALSE

1. In a star topology, a single connection failure will halt all traffic between all sites.

ANS: F PTS: 1 REF: 297

2. Dial-up ISDN does not convert a computer’s digital signals to analog before transmitting them over the PSTN.

ANS: T PTS: 1 REF: 306

3. ATM is a WAN technology that functions in the Data Link layer.

ANS: T PTS: 1 REF: 320

4. SONET specifies framing and multiplexing techniques at the Physical layer.

ANS: T PTS: 1 REF: 321

5. After SONET, BPL has the best maximum throughput available.

ANS: F PTS: 1 REF: 325

MULTIPLE CHOICE

1. WANs typically send data over ____ available communications networks.

a.

privately

c.

individually

b.

publicly

d.

serially

ANS: B PTS: 1 REF: 294

2. The individual geographic locations connected by a WAN are known as ____.

a.

WAN sites

c.

network service providers

b.

WAN links

d.

central offices

ANS: B PTS: 1 REF: 294

3. Because WAN connections require routers or other Layer 3 devices to connect locations, their links are not capable of carrying ____ protocols.

a.

open

c.

routable

b.

standard

d.

nonroutable

ANS: D PTS: 1 REF: 294

4. On most modern WANs, a ring topology relies on ____ rings to carry data.

a.

flexible

c.

serial

b.

open

d.

redundant

ANS: D PTS: 1 REF: 296

5. ____ WANs are the most fault-tolerant type of WAN because they provide multiple routes for data to follow between any two points.

a.

Bus

c.

Mesh

b.

Star

d.

Tiered

ANS: C PTS: 1 REF: 298

6. The ____ encompasses the entire telephone system, from the wires that enter homes and businesses to the network centers that connect different regions of a country.

a.

SLIP

c.

PPP

b.

POTS

d.

PSTN

ANS: D PTS: 1 REF: 299-300

7. A(n) ____ is the place where a telephone company terminates lines and switches calls between different locations.

a.

CO

c.

DO

b.

EO

d.

TO

ANS: A PTS: 1 REF: 300

8. A ____ connection is one in which a user connects her computer, via a modem, to a distant network and stays connected for a finite period of time.

a.

remote

c.

dial-up

b.

direct

d.

virtual

ANS: C PTS: 1 REF: 300

9. The portion of the PSTN that connects any residence or business to the nearest CO is known as the ____.

a.

demarcation point

c.

local loop

b.

NIU (Network Interface Unit)

d.

central office

ANS: C PTS: 1 REF: 302

10. ____ means that a telephone company connects residential users to its network with fiber-optic cable.

a.

OLT

c.

PON

b.

FITL

d.

FITH

ANS: D PTS: 1 REF: 302

11. ____ is an updated, digital version of X.25 that also relies on packet switching.

a.

DSL

c.

Frame relay

b.

ISDN

d.

ATM

ANS: C PTS: 1 REF: 304

12. In a process called ____, two 64-Kbps ISDN B channels can be combined to achieve an effective throughput of 128 Kbps.

a.

slicing

c.

merging

b.

linking

d.

bonding

ANS: D PTS: 1 REF: 306

13. A ____ converts digital signals into analog signals for use with ISDN phones and other analog devices.

a.

terminal adapter

c.

smart jack

b.

DSLAM

d.

terminator

ANS: A PTS: 1 REF: 306-307

14. ISDN PRI uses ____ B channels and one 64-Kbps D channel.

a.

10

c.

23

b.

12

d.

32

ANS: C PTS: 1 REF: 307

15. The speed of a T-carrier depends on its ____ level.

a.

signal

c.

channel

b.

hierarchy

d.

traffic

ANS: A PTS: 1 REF: 309

16. At the customer’s demarcation point, either inside or outside the building, RJ-48 connectors terminate in a ____.

a.

terminal adapter

c.

CSU/DSU

b.

smart jack

d.

switch

ANS: B PTS: 1 REF: 311

17. A ____ aggregates multiple DSL subscriber lines and connects them to the carrier’s CO.

a.

terminal adapter

c.

smart jack

b.

DSLAM

d.

terminator

ANS: B PTS: 1 REF: 317

18. Broadband cable requires many subscribers to share the same local line, thus raising concerns about ____ and actual (versus theoretical) throughput.

a.

access

c.

noise

b.

costs

d.

security

ANS: D PTS: 1 REF: 319

19. What sets ATM apart from Ethernet is its ____ size.

a.

channel

c.

variable packet

b.

frame

d.

fixed packet

ANS: D PTS: 1 REF: 320

20. SONET’s extraordinary ____ results from its use of a double-ring topology over fiber-optic cable.

a.

throughput

c.

fault tolerance

b.

low cost

d.

latency

ANS: C PTS: 1 REF: 322

21. The data rate of a particular SONET ring is indicated by its ____, a rating that is internationally recognized by networking professionals and standards organizations.

a.

OC (Optical Carrier) level

c.

BRI (Basic Rate Interface)

b.

CIR (committed information rate)

d.

DS0 (digital signal, level 0)

ANS: A PTS: 1 REF: 324

COMPLETION

1. ____________________ are connections between network nodes that, although based on potentially disparate physical links, logically appear to be direct, dedicated links between those nodes.

ANS: Virtual circuits

PTS: 1 REF: 304

2. A(n) ____________________ uses TDM (time division multiplexing) over two wire to divide a single channel into multiple channels.

ANS: T-carrier

PTS: 1 REF: 308

3. ____________________ encapsulates incoming Ethernet or token ring frames, then converts them into ATM cells for transmission over an ATM network.

ANS:

LANE (LAN Emulation)

LAN Emulation

LANE

PTS: 1 REF: 321

4. A(n) ____________________ node in synchronous communications recognizes that it should be receiving data by looking at the time on the clock.

ANS: receiving

PTS: 1 REF: 322

5. A(n) ____________________ combines individual SONET signals on the transmitting end, and another multiplexer separates combined signals on the receiving end.

ANS: multiplexer

PTS: 1 REF: 323

MATCHING

Match each item with a statement below:

a.

bus topology WAN

f.

upstream

b.

star topology WAN

g.

asymmetrical communications

c.

mesh topology WAN

h.

symmetrical technology

d.

tiered topology WAN

i.

signal level

e.

downstream

1. Contain sites that are connected in star or ring formations are interconnected at different levels, with the interconnection points being organized into layers to form hierarchical groupings.

2. Occurs when data travels from the carrier’s switching facility to the customer.

3. Contains a single site acting as the central connection point for several other points.

4. Occurs when downstream throughput is higher than upstream throughput.

5. Refers to the T-carrier’s Physical layer electrical signaling characteristics as defined by ANSI standards in the early 1980s.

6. Occurs when data travels from the customer to the carrier’s switching facility.

7. Occurs when each site is directly connected to no more than two other sites in a serial fashion.

8. Provides equal capacity for data traveling both upstream and downstream.

9. Incorporates many directly interconnected sites.

1. ANS: D PTS: 1 REF: 298

2. ANS: E PTS: 1 REF: 314

3. ANS: B PTS: 1 REF: 297

4. ANS: G PTS: 1 REF: 314

5. ANS: I PTS: 1 REF: 309

6. ANS: F PTS: 1 REF: 314

7. ANS: A PTS: 1 REF: 295

8. ANS: H PTS: 1 REF: 314

9. ANS: C PTS: 1 REF: 298

SHORT ANSWER

1. Describe the fundamental properties WANs and LANs have in common.

ANS:

WANs and LANs have several fundamental properties in common. Both are designed to enable communication between clients and hosts for resource sharing. In general, both use the same protocols from Layers 3 and higher of the OSI model. And both networks typically carry digitized data via packet-switched connections.

PTS: 1 REF: 294

2. Define and describe a PSTN.

ANS:

PSTN, which stands for Public Switched Telephone Network, refers to the network of lines and carrier equipment that provides telephone service to most homes and businesses. PSTN may also be called POTS (plain old telephone service). The PSTN encompasses the entire telephone system, from the wires that enter homes and businesses to the network centers that connect different regions of a country.

PTS: 1 REF: 299-300

3. Describe an important difference between frame relay and X.25.

ANS:

An important difference between frame relay and X.25 is that frame relay does not guarantee reliable delivery of data. X.25 checks for errors and, in the case of an error, either corrects the damaged data or retransmits the original data. Frame relay, on the other hand, simply checks for errors. It leaves the error correction up to higher-layer protocols.

PTS: 1 REF: 304

4. Define a fractional T1 and explain why an organization might implement it.

ANS:

A fractional T1 lease allows organizations to use only some of the channels on a T1 line and be charged according to the number of channels they use. Thus, fractional T1 bandwidth can be leased in multiples of 64 Kbps. A fractional T1 is best suited to businesses that expect their traffic to grow and that may require a full T1 eventually, but can’t currently justify leasing a full T1.

PTS: 1 REF: 310

5. Define the term xDSL and name the better known DSL varieties.

ANS:

The term xDSL refers to all DSL varieties, of which at least eight currently exist. The better known DSL varieties include ADSL (Asymmetric DSL), G.Lite (a version of ADSL), HDSL (High Bit-Rate DSL), SDSL (Symmetric or Single-Line DSL), VDSL (Very High Bit-Rate DSL), and SHDSL (Single-Line High Bit-Rate DSL) – the x in xDSL is replaced by the variety name.

PTS: 1 REF: 314

6. Explain how a cable modem is utilized in broadband cable connections.

ANS:

Broadband cable connections require that the customer use a special cable modem, a device that modulates and demodulates signals for transmission and reception via cable wiring. Cable modems operate at the Physical and Data Link layer of the OSI model, and, therefore, do not manipulate higher-layer protocols, such as IP. The cable modem then connects to a customer’s PC via an RJ-45, USB, or wireless interface to a NIC. Alternately, the cable modem could connect to a connectivity device, such as a hub, switch, or router, thereby supplying bandwidth to a LAN rather than to just one computer. It’s also possible to use a device that combines cable modem functionality with a router; this single device can then provide both the broadband cable connection and the capability of sharing the bandwidth between multiple nodes.

PTS: 1 REF: 318

7. Explain how ATM relies on virtual circuits.

ANS:

Like X.25 and frame relay, ATM relies on virtual circuits. On an ATM network, switches determine the optimal path between the sender and receiver, then establish this path before the network transmits data. Because ATM packages data into cells before transmission, each of which travels separately to its destination, ATM is typically considered a packet-switching technology. At the same time, the use of virtual circuits means that ATM provides the main advantage of circuit switching – that is, a point-to-point connection that remains reliably available to the transmission until it completes, making ATM a connection-oriented technology.

PTS: 1 REF: 321

8. List and describe the key strengths of SONET.

ANS:

Its four key strengths are that it can integrate many other WAN technologies, it offers fast data transfer rates, it allows for simple link additions and removals, and it provides a high degree of fault tolerance.

PTS: 1 REF: 321-322

9. Describe the most important advantage of SONET.

ANS:

Perhaps the most important SONET advantage is that it provides interoperability. Before SONET, telecommunications carriers that used different signaling techniques (or even the same technique but different equipment) could not be assured that their networks could communicate. Now, SONET is often used to aggregate multiple T1s, T3s, or ISDN lines. SONET is also used as the underlying technology for ATM transmission. Furthermore, because it can work directly with the different standards used in different countries, SONET has emerged as the best choice for linking WANs between North America, Europe, and Asia. Internationally, SONET is known as SDH (Synchronous Digital Hierarchy).

PTS: 1 REF: 322

10. Why is SONET technology typically not implemented by small or medium-size businesses?

ANS:

SONET technology is typically not implemented by small or medium-sized businesses because of its high cost.

PTS: 1 REF: 324

Chapter 7:Wide Area Networks

TRUE/FALSE

1. In a star topology, a single connection failure will halt all traffic between all sites.

ANS: F PTS: 1 REF: 297

2. Dial-up ISDN does not convert a computer’s digital signals to analog before transmitting them over the PSTN.

ANS: T PTS: 1 REF: 306

3. ATM is a WAN technology that functions in the Data Link layer.

ANS: T PTS: 1 REF: 320

4. SONET specifies framing and multiplexing techniques at the Physical layer.

ANS: T PTS: 1 REF: 321

5. After SONET, BPL has the best maximum throughput available.

ANS: F PTS: 1 REF: 325

MULTIPLE CHOICE

1. WANs typically send data over ____ available communications networks.

a.

privately

c.

individually

b.

publicly

d.

serially

ANS: B PTS: 1 REF: 294

2. The individual geographic locations connected by a WAN are known as ____.

a.

WAN sites

c.

network service providers

b.

WAN links

d.

central offices

ANS: B PTS: 1 REF: 294

3. Because WAN connections require routers or other Layer 3 devices to connect locations, their links are not capable of carrying ____ protocols.

a.

open

c.

routable

b.

standard

d.

nonroutable

ANS: D PTS: 1 REF: 294

4. On most modern WANs, a ring topology relies on ____ rings to carry data.

a.

flexible

c.

serial

b.

open

d.

redundant

ANS: D PTS: 1 REF: 296

5. ____ WANs are the most fault-tolerant type of WAN because they provide multiple routes for data to follow between any two points.

a.

Bus

c.

Mesh

b.

Star

d.

Tiered

ANS: C PTS: 1 REF: 298

6. The ____ encompasses the entire telephone system, from the wires that enter homes and businesses to the network centers that connect different regions of a country.

a.

SLIP

c.

PPP

b.

POTS

d.

PSTN

ANS: D PTS: 1 REF: 299-300

7. A(n) ____ is the place where a telephone company terminates lines and switches calls between different locations.

a.

CO

c.

DO

b.

EO

d.

TO

ANS: A PTS: 1 REF: 300

8. A ____ connection is one in which a user connects her computer, via a modem, to a distant network and stays connected for a finite period of time.

a.

remote

c.

dial-up

b.

direct

d.

virtual

ANS: C PTS: 1 REF: 300

9. The portion of the PSTN that connects any residence or business to the nearest CO is known as the ____.

a.

demarcation point

c.

local loop

b.

NIU (Network Interface Unit)

d.

central office

ANS: C PTS: 1 REF: 302

10. ____ means that a telephone company connects residential users to its network with fiber-optic cable.

a.

OLT

c.

PON

b.

FITL

d.

FITH

ANS: D PTS: 1 REF: 302

11. ____ is an updated, digital version of X.25 that also relies on packet switching.

a.

DSL

c.

Frame relay

b.

ISDN

d.

ATM

ANS: C PTS: 1 REF: 304

12. In a process called ____, two 64-Kbps ISDN B channels can be combined to achieve an effective throughput of 128 Kbps.

a.

slicing

c.

merging

b.

linking

d.

bonding

ANS: D PTS: 1 REF: 306

13. A ____ converts digital signals into analog signals for use with ISDN phones and other analog devices.

a.

terminal adapter

c.

smart jack

b.

DSLAM

d.

terminator

ANS: A PTS: 1 REF: 306-307

14. ISDN PRI uses ____ B channels and one 64-Kbps D channel.

a.

10

c.

23

b.

12

d.

32

ANS: C PTS: 1 REF: 307

15. The speed of a T-carrier depends on its ____ level.

a.

signal

c.

channel

b.

hierarchy

d.

traffic

ANS: A PTS: 1 REF: 309

16. At the customer’s demarcation point, either inside or outside the building, RJ-48 connectors terminate in a ____.

a.

terminal adapter

c.

CSU/DSU

b.

smart jack

d.

switch

ANS: B PTS: 1 REF: 311

17. A ____ aggregates multiple DSL subscriber lines and connects them to the carrier’s CO.

a.

terminal adapter

c.

smart jack

b.

DSLAM

d.

terminator

ANS: B PTS: 1 REF: 317

18. Broadband cable requires many subscribers to share the same local line, thus raising concerns about ____ and actual (versus theoretical) throughput.

a.

access

c.

noise

b.

costs

d.

security

ANS: D PTS: 1 REF: 319

19. What sets ATM apart from Ethernet is its ____ size.

a.

channel

c.

variable packet

b.

frame

d.

fixed packet

ANS: D PTS: 1 REF: 320

20. SONET’s extraordinary ____ results from its use of a double-ring topology over fiber-optic cable.

a.

throughput

c.

fault tolerance

b.

low cost

d.

latency

ANS: C PTS: 1 REF: 322

21. The data rate of a particular SONET ring is indicated by its ____, a rating that is internationally recognized by networking professionals and standards organizations.

a.

OC (Optical Carrier) level

c.

BRI (Basic Rate Interface)

b.

CIR (committed information rate)

d.

DS0 (digital signal, level 0)

ANS: A PTS: 1 REF: 324

COMPLETION

1. ____________________ are connections between network nodes that, although based on potentially disparate physical links, logically appear to be direct, dedicated links between those nodes.

ANS: Virtual circuits

PTS: 1 REF: 304

2. A(n) ____________________ uses TDM (time division multiplexing) over two wire to divide a single channel into multiple channels.

ANS: T-carrier

PTS: 1 REF: 308

3. ____________________ encapsulates incoming Ethernet or token ring frames, then converts them into ATM cells for transmission over an ATM network.

ANS:

LANE (LAN Emulation)

LAN Emulation

LANE

PTS: 1 REF: 321

4. A(n) ____________________ node in synchronous communications recognizes that it should be receiving data by looking at the time on the clock.

ANS: receiving

PTS: 1 REF: 322

5. A(n) ____________________ combines individual SONET signals on the transmitting end, and another multiplexer separates combined signals on the receiving end.

ANS: multiplexer

PTS: 1 REF: 323

MATCHING

Match each item with a statement below:

a.

bus topology WAN

f.

upstream

b.

star topology WAN

g.

asymmetrical communications

c.

mesh topology WAN

h.

symmetrical technology

d.

tiered topology WAN

i.

signal level

e.

downstream

1. Contain sites that are connected in star or ring formations are interconnected at different levels, with the interconnection points being organized into layers to form hierarchical groupings.

2. Occurs when data travels from the carrier’s switching facility to the customer.

3. Contains a single site acting as the central connection point for several other points.

4. Occurs when downstream throughput is higher than upstream throughput.

5. Refers to the T-carrier’s Physical layer electrical signaling characteristics as defined by ANSI standards in the early 1980s.

6. Occurs when data travels from the customer to the carrier’s switching facility.

7. Occurs when each site is directly connected to no more than two other sites in a serial fashion.

8. Provides equal capacity for data traveling both upstream and downstream.

9. Incorporates many directly interconnected sites.

1. ANS: D PTS: 1 REF: 298

2. ANS: E PTS: 1 REF: 314

3. ANS: B PTS: 1 REF: 297

4. ANS: G PTS: 1 REF: 314

5. ANS: I PTS: 1 REF: 309

6. ANS: F PTS: 1 REF: 314

7. ANS: A PTS: 1 REF: 295

8. ANS: H PTS: 1 REF: 314

9. ANS: C PTS: 1 REF: 298

SHORT ANSWER

1. Describe the fundamental properties WANs and LANs have in common.

ANS:

WANs and LANs have several fundamental properties in common. Both are designed to enable communication between clients and hosts for resource sharing. In general, both use the same protocols from Layers 3 and higher of the OSI model. And both networks typically carry digitized data via packet-switched connections.

PTS: 1 REF: 294

2. Define and describe a PSTN.

ANS:

PSTN, which stands for Public Switched Telephone Network, refers to the network of lines and carrier equipment that provides telephone service to most homes and businesses. PSTN may also be called POTS (plain old telephone service). The PSTN encompasses the entire telephone system, from the wires that enter homes and businesses to the network centers that connect different regions of a country.

PTS: 1 REF: 299-300

3. Describe an important difference between frame relay and X.25.

ANS:

An important difference between frame relay and X.25 is that frame relay does not guarantee reliable delivery of data. X.25 checks for errors and, in the case of an error, either corrects the damaged data or retransmits the original data. Frame relay, on the other hand, simply checks for errors. It leaves the error correction up to higher-layer protocols.

PTS: 1 REF: 304

4. Define a fractional T1 and explain why an organization might implement it.

ANS:

A fractional T1 lease allows organizations to use only some of the channels on a T1 line and be charged according to the number of channels they use. Thus, fractional T1 bandwidth can be leased in multiples of 64 Kbps. A fractional T1 is best suited to businesses that expect their traffic to grow and that may require a full T1 eventually, but can’t currently justify leasing a full T1.

PTS: 1 REF: 310

5. Define the term xDSL and name the better known DSL varieties.

ANS:

The term xDSL refers to all DSL varieties, of which at least eight currently exist. The better known DSL varieties include ADSL (Asymmetric DSL), G.Lite (a version of ADSL), HDSL (High Bit-Rate DSL), SDSL (Symmetric or Single-Line DSL), VDSL (Very High Bit-Rate DSL), and SHDSL (Single-Line High Bit-Rate DSL) – the x in xDSL is replaced by the variety name.

PTS: 1 REF: 314

6. Explain how a cable modem is utilized in broadband cable connections.

ANS:

Broadband cable connections require that the customer use a special cable modem, a device that modulates and demodulates signals for transmission and reception via cable wiring. Cable modems operate at the Physical and Data Link layer of the OSI model, and, therefore, do not manipulate higher-layer protocols, such as IP. The cable modem then connects to a customer’s PC via an RJ-45, USB, or wireless interface to a NIC. Alternately, the cable modem could connect to a connectivity device, such as a hub, switch, or router, thereby supplying bandwidth to a LAN rather than to just one computer. It’s also possible to use a device that combines cable modem functionality with a router; this single device can then provide both the broadband cable connection and the capability of sharing the bandwidth between multiple nodes.

PTS: 1 REF: 318

7. Explain how ATM relies on virtual circuits.

ANS:

Like X.25 and frame relay, ATM relies on virtual circuits. On an ATM network, switches determine the optimal path between the sender and receiver, then establish this path before the network transmits data. Because ATM packages data into cells before transmission, each of which travels separately to its destination, ATM is typically considered a packet-switching technology. At the same time, the use of virtual circuits means that ATM provides the main advantage of circuit switching – that is, a point-to-point connection that remains reliably available to the transmission until it completes, making ATM a connection-oriented technology.

PTS: 1 REF: 321

8. List and describe the key strengths of SONET.

ANS:

Its four key strengths are that it can integrate many other WAN technologies, it offers fast data transfer rates, it allows for simple link additions and removals, and it provides a high degree of fault tolerance.

PTS: 1 REF: 321-322

9. Describe the most important advantage of SONET.

ANS:

Perhaps the most important SONET advantage is that it provides interoperability. Before SONET, telecommunications carriers that used different signaling techniques (or even the same technique but different equipment) could not be assured that their networks could communicate. Now, SONET is often used to aggregate multiple T1s, T3s, or ISDN lines. SONET is also used as the underlying technology for ATM transmission. Furthermore, because it can work directly with the different standards used in different countries, SONET has emerged as the best choice for linking WANs between North America, Europe, and Asia. Internationally, SONET is known as SDH (Synchronous Digital Hierarchy).

PTS: 1 REF: 322

10. Why is SONET technology typically not implemented by small or medium-size businesses?

ANS:

SONET technology is typically not implemented by small or medium-sized businesses because of its high cost.

PTS: 1 REF: 324