Chapter 9
Wide Area Networks
True-False Questions
The following are possible True/False questions for tests. The statement is given and the answer
is provided . The level of difficulty (easy, medium, hard) and the section(s) relevant to the topic
are also furnished.
1.
In building Wide Area Networks, many organizations do not build their own long distance
communication circuits
2.
WANs can connect BNs across distances that can span up to thousands of miles.
3.
Common carriers sell or lease communication services and facilities to the public.
4.
Today, a common carrier that provides long distance services is typically called a local
exchange carrier.
5.
A dedicated circuit is usually not available late at nights or on weekends.
6.
A WAN with a ring topology can use full or half duplex circuits
7.
A disadvantage of a star architecture is that the failure of one circuit will disrupt the entire
network.
8.
Full mesh networks are inexpensive.
9.
Full mesh design networks are more common than partial mesh design networks.
10. `
T carrier circuits can only be used to transmit voice.
11.
A T1 circuit provides a data rate of 1.544Mbps.
12.
SONET is made up of very high speed dedicated circuits that incorporate inverse
multiplexing (IMUX) for all levels above the OC-1 level.
13.
An OC-1 circuit provides a data rate of 155 Mbps.
14.
To connect into a packet switched network, a network terminator is generally used.
15.
Packet switched networks enable packets from separate messages or separate organizations
to be interleaved for transmission.
16.
Datagrams are connection-oriented.
17.
The committed information rate (CIR) in a permanent virtual circuit is the maximum
allowable rate that the network will attempt to provide.
L.O.: Understand packet-switched services and architectures
18.
Frame relay is a reliable packet service.
19.
Ethernet/IP packet networks are not provided by common carriers such as AT&T.
20.
Virtual private networks permit users to create permanent virtual circuits, or tunnels, through
the Internet.
21.
MPLS operate at layer 4.
22.
VPNs offer high security because they operate through the Internet.
23.
An intranet VPN connects different organizations over the Internet.
MULTIPLE CHOICE
The following are possible multiple-choice questions for tests. The question is posed and the
answer is provided under the choices. The level of difficulty (easy, medium, hard) and the
section(s) relevant to the topic is also furnished.
1.
____________ are companies that build a data and telecommunications infrastructure from
which other companies can lease services for WANs and MANs.
a. Common carriers
b. Router manufacturers
c. Standards organizations
d. CSUs
e. PUCs
L.O.: Understand the best practice recommendations for WAN design
2.
Each state or Canadian province has its own ___________ to regulate communications
within its borders.
a. CRTC
b. Federal Communications Commission
c. common carriers
d. public utilities commission
e. PTT
3.
The _________________ is a Canadian government agency that regulates voice and data
communication.
a. PSTN
b. FCC
c. CRTC
d. CSU
e. POTS
L.O.: Understand the best practice recommendations for WAN design
4.
Basic rate interface:
a. is typically offered only to commercial customers
b. provides a communications circuit with two 64 Kbps B channels, plus one D channel
c. is defined exactly the same way in Europe
d. has an upper capacity of 1.544 Mbps
e. is comprised of analog circuits only
5.
Primary rate interface:
a. is typically offered only to commercial customers
b. provides a communications circuit with two 64 Kbps B channels, plus one D channel
c. is defined exactly the same way in Europe
d. has an upper capacity of 128Kbps
e. is comprised of analog circuits only
6.
A ___________ is/are devices that permit a user to connect to a digital T-carrier service.
a. modem
b. codec
c. CSU/DSU
d. NIC
e. ATM
7.
Which of the following is not a basic architecture for dedicated circuit networks?
a. ring
b. partial mesh
c. bus
d. star
e. full mesh
8.
A ________ geometric layout connects all computers in a closed loop, with each computer
linked to the next usually with a series of point-to-point dedicated circuits.
a. bus design
b. star design
c. full mesh design
d. ring design
e. partial mesh design
9.
In a ring design WAN,
a. messages can take a long time to travel from the sender to the receiver
b. a message arrives at all computers on the network simultaneously
c. messages always arrive faster than in other types of layouts
d. messages are delivered directly from sender to receiver because there is a point–to–
point connection directly between each sender and each receiver
e. messages always take one second to travel between sender and receiver
10.
In a ring design WAN,
a. failure in one circuit means that the network can most likely continue to function
b. failure in one circuit always means that the network will cease to function
c. failure in one computer always means that the network will cease to function
d. failure in one circuit means that there will not be any increased traffic delays in the
network
e. failure in one computer always means that messages will stop at that computer since
it would be impossible to re-route traffic
11.
A star architecture:
a. connects all computers in a closed loop
b. connects all computers off a backbone circuit
c. connects all computers to one central computer that routes messages to the
appropriate computer
d. all of the above
e. none of the above
12.
A _______ geometric layout for a WAN connects all computers to one central computer that
routes messages to the appropriate computer, usually via a series of point–to-point dedicated
circuits.
a. ring design
b. mesh design
c. bus design
d. star design
e. mesh design
13.
A star topology is:
a. difficult to manage because the central computer receives and routes all messages in
the network
b. dependent upon the capacity of the central computer for its performance
c. always slower than a ring network
d. less susceptible to traffic problems than other architectures
e. not affected if the central computer fails
14.
In ______ geometric layout for a network, every computer is connected to every other
computer often by point-to-point dedicated circuits.
a. full mesh design
b. ring design
c. star design
d. bus design
e. partial mesh design
15.
Mesh networks:
a. usually provide relatively long routes through the network (compared to ring
networks)
b. require more processing by each computer in the network than in star or ring
networks
c. do not use decentralized routing
d. do not have much capacity wasted by network status information
e. do not have many possible routes through the network to prevent one circuit from
becoming overloaded
16.
_____ are dedicated digital circuits that are the most commonly used form of dedicated
circuit services in North America today.
a. Wideband analog services
b. SMDS
c. ATM
d. T-carrier services
e. ISDN
17.
The data rate for a T-1 circuit in North America is:
a. 1.544 Mbps
b. 6.312 Mbps
c. 44.376 Mbps
d. 274.176 Mbps
e. 1.544 Gbps
18.
In North America, a T1 circuit has ______ 64Kbps channels.
a. 2
b. 30
c. 24
d. 12
e. 36
19.
The data rate for a T-3 circuit in North America is:
a. 1.544 Mbps
b. 6.312 Mbps
c. 44.376 Mbps
d. 274.176 Mbps
e. 1.544 Gbps
20.
SONET:
a. is a standard for optical transmission that currently operates at Terabit per second
speeds
b. is very similar to the ITU-T standard, synchronous digital hierarchy
c. uses inverse multiplexing above the OC-1 level
d. refers to Sprint Overall Network
e. is not currently available, even in large cities
21.
Which of the following is not a benefit of packet switched services?
a. The data transmission rates tend to be lower than dial-up or dedicated circuits.
b. You don’t have to set up dedicated circuits between each end point from and to
which you wish to transmit data and/or voice.
c. You have the flexibility to send data through a temporary circuit between two
connections that will be disconnected as soon as the digital transmission is
completed.
d. All circuits are less susceptible to a great deal of noise because they are digital.
e. You don’t have to specify all the interconnecting services you need for your WAN
when you buy the service.
22.
A _____________ is a user’s connection into a packet switched service.
a. packet analog/digital device
b. packet asynchronous/discrete device
c. packet asymmetric/data transmission device
d. packet assembly/disassembly device
e. packet analyzer/decoder device
23.
Which of the following type of networks permit packets from separate messages to be
interleaved?
a. circuit switched network
b. dedicated circuit network
c. dial up circuit network
d. packet switched network
e. Fractional T-1 network
24.
A _______ is a connectionless method of sending data packets on a packet switched service.
a. bursty packet
b. virtual circuit
c. datagram
d. histogram
e. permanent virtual circuit
25.
A _________ is a connection-oriented approach to sending packets on a packet switched
service.
a. permanent virtual circuit
b. datagram
c. histogram
d. bursty packet
e. fractional T-1 network
26.
In a packet switched network, permanent virtual circuits that look very similar to a
_____________ (for hardware-based dedicated circuits) move packets through the network.
a. cloud-based ring design
b. cloak-based mesh design
c. cloud-based mesh design
d. common carrier ring design
e. common carrier bus design
27.
______________ are sometimes called private line services.
a. WANs
b. LANs
c. Circuit-switched networks
d. Dedicated-circuit networks
e. Routed-backbone networks
28.
OC-3072 has a data rate of
a. 159.25 Gbps
b. 39.813 Gbps
c. 1.544 Mbps
d. 100 Mbps
e. 1.244 Gbps
29.
_____________ is sometimes called a Layer 2.5 technology.
a. ATM
b. MPLS
c. Ethernet
d. TCP
e. IP
30.
Ethernet/IP packet networks:
a. are supported with gigabit fiber optic networks in large cities
b. are offered only by the common carriers
c. use token ring layer 2 media access control
d. use IPX/SPX protocols
e. provide CIR up to a maximum of 1.544 Mbps
31.
A _______________ is a particular type of network that uses circuits that run over the
Internet but that appears to the user to be a private network.
a. local carrier network
b. virtual private network
c. integrated service digital network
d. software defined network
e. SONET network
32.
With a virtual private network, users create permanent virtual circuits through the Internet
called:
a. bursts
b. cells
c. tunnels
d. rings
e. clouds
33.
Which of the following is a primary advantage of a VPN?
a. low cost
b. inflexibility
c. unpredictable traffic congestion
d. security
e. complexity to the user
34.
_____________ is a common standard for use by layer 2 access VPNs for encapsulation.
a. L2TP
b. VPN2
c. Encapsule2
d. TCP/IP
e. PPP
35.
Which of the following is not a type of VPN?
a. intranet VPN
b. extranet VPN
c. access VPN
d. T-1 VPN
e. a VPN that enables employees to access an organization’s network from a remote
location
L.O.: Understand Internet-based VPN services and architectures
36.
__________ is a term that refers to the speed in converting input packets to output packets.
a. Transfer mode
b. Latency
c. Burstiness
d. Cell relay
e. Frame relay
Answer: B
37.
The performance of WANs can be improved by:
a. upgrading the circuits between the computers
b. increasing the demand placed on the network
c. downgrading the circuits between the computers
d. downgrading the devices that provide access to the circuits
e. increasing network traffic
Answer: A
38.
Dynamic routing:
a. imposes an overhead cost by increasing network traffic
b. decreases performance in networks which have many possible routes
c. decreases performance in networks with “bursty” traffic
d. should be used in 80 to 90 percent of total networks’ capacity
e. is another term for static routing in WANs
Answer: A
39.
Which of the following is not a way to reduce network demand?
a. shifting network usage from high cost times to lower cost times
b. using data compression techniques for all data in the network
c. requiring a network impact statement for all application software developed by the
organization
d. moving data further from the applications and people who use them
e. shifting network usage from peak to lower demand times
40.
Which of the following is not a key issue to be considered when selecting a WAN service?
a. prestige value of using a particular common carrier
b. flexibility
c. capacity
d. control
e. reliability
41.
With IP services, the ________ at the sending site takes the outgoing message (which usually
is an Ethernet frame containing an IP packet), strips off the Ethernet frame and uses the IP
address in the IP packet to route the packet though the carrier’s packet‐switched network to
its final destination.
a. PAD
b. gateway
c. switch
d. router
e. WAN
42.
Most IP services use _______ as the data link layer protocol.
a. Ethernet
b. TCP
c. MPLS
d. IRoute
e. T1
Short Answer and Essay Questions:
1. Using a chart format, list, define and briefly describe two dedicated circuit
services and two packet switched services.
2. Draw a diagram of packet switched service, and describe packet switching
concepts.
3. How does a SVC differ from a PVC?
4. Explain the differences between CIR and MAR.
5. Where does packetizing take place?
6. Compare and contrast frame relay, MPLS and Ethernet service networks.
7. Describe six ways in which a network manager might improve WAN service.
8. Suppose you joined a company that had a WAN composed of SONET, T carrier
services, and frame relay, each selected to match a specific network need for a
certain set of circuits. Would you say this was a well-designed network?
Explain.
9. What are the main benefits of using a VPN?
10. Describe the three types of VPN.
11. What are the benefits of IP services over other packet-switched options?
12. Compare the ring, star, and mesh architectures. Provide one example of when
each one might be better to use compared to the others.
13.