SSD8-1
.docYour score on this question is: 10.00
Feedback:
See section 1.3.2 of the course notes.
--------------------------------------------------------------------------------
9.
Which of the following benefit from "tunneling" IP datagrams by conveying them inside other packets?
Mobile IP
Multicast
Roll-out of IPv6
(a) I and III only
(b) none
(c) I, II and III
(d) II only
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.3.8 of the course notes.
--------------------------------------------------------------------------------
10.
The main network engineer of a large corporation is charged with designing and deploying the company's intranet. She has decided to use a connection-oriented network layer. Which of the following concerns do you think motivated her choice?
(a) Cost of the routers as the network grows
(b) Ability to reserve bandwidth—e.g., for important presentations to the Board
(c) Cost of short transactions—e.g., credit card charge approval.
(d) Ability to re-route traffic around congested links
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.3.1 of the course notes.
1.
Do most distributed applications require a complete ordering of events?
(a) Yes, and they must know the exact time.
(b) Yes, but they do not need to know the exact time.
(c) No, most distributed applications only need a partial ordering of events.
(d) No, most distributed applications are designed so that the order of events doesn't matter.
Correct answer is (c)
Your score on this question is: 16.67
Feedback:
See section 3.1.2 of the course notes.
--------------------------------------------------------------------------------
2.
Which of the following are true?
The happens-before relation is transitive.
Disjoint events can have the same logical time.
(a) II only
(b) I and II
(c) I only
(d) None
Correct answer is (b)
Your score on this question is: 16.67
Feedback:
See section 3.1.2 of the course notes.
--------------------------------------------------------------------------------
3.
Which of the following can PGP provide?
Message integrity checking
Sender authentication
Secrecy
(a) III only
(b) I and II only
(c) I and III only
(d) I, II, and III
Correct answer is (d)
Your score on this question is: 16.67
Feedback:
See section 3.1.6 of the course notes.
--------------------------------------------------------------------------------
4.
A client sends a secure http request to a server that uses SSL. The server responds with a certificate. What is the data in the certificate?
(a) The client's public key encrypted, using the server's private key
(b) The client's public key encrypted, using the secret key of a certification authority
(c) The server's public key encrypted, using the secret key of a certification authority
(d) A certification authority's public key encrypted, using the server's private key
Correct answer is (c)
Your score on this question is: 16.67
Feedback:
See section 3.1.6 of the course notes.
--------------------------------------------------------------------------------
5.
Which of the following are advantages of stateless distributed file systems?
Limited complexity on the file server
Prevents inconsistencies by preventing conflicting file access
(a) II only
(b) I and II
(c) None
(d) I only
Correct answer is (d)
Your score on this question is: 16.67
Feedback:
See section 3.1.4 of the course notes.
--------------------------------------------------------------------------------
6.
Which of the following statements are true?
Working on several tasks at the same time in an interleaved fashion can sometimes improve throughput without increasing response time.
It is sometimes not possible to both maximize throughput and minimize response time.
(a) II only
(b) I only
(c) I and II
(d) None
Correct answer is (c)
Your score on this question is: 16.67
Feedback:
See section 3.1.3 of the course notes.
1.
Which of the following are true of CORBA's dynamic discovery of interfaces?
Parameter values are matched by the number and type of the parameters.
Parameter values can be provided by a human user at run time.
(a) I only
(b) II only
(c) I and II
(d) None
Correct answer is (b)
Your score on this question is: 20.00
Feedback:
See section 3.3.2 of the course notes.
--------------------------------------------------------------------------------
2.
Which of the following stubs does the IDL compiler generate?
Client stubs
Server stubs
(a) None
(b) I and II
(c) I only
(d) II only
Correct answer is (b)
Your score on this question is: 20.00
Feedback:
See section 3.3.2 of the course notes.
--------------------------------------------------------------------------------
3.
Which of the following are supported by Jini?
Entire object passing
Discovery service that looks up services based on a set of attributes
(a) None
(b) II only
(c) I and II
(d) I only
Correct answer is (c)
Your score on this question is: 20.00
Feedback:
See section 3.3.3 of the course notes.
--------------------------------------------------------------------------------
4.
In a traditional distributed computing environment, _____ decides what services are needed and configures a set of servers to provide those services.
(a) a central server
(b) a process load table
(c) the user
(d) the system manager
Correct answer is (d)
Your score on this question is: 20.00
Feedback:
See section 3.3.1 of the course notes.
--------------------------------------------------------------------------------
5.
Which of the following statements are true about CORBA?
Using the CORBA IDL, existing code written in procedural languages can be made to look like objects using IDL wrappers
IDL code can be generated automatically from the code of many OO languages
The IDL code can be used to generate implementation code automatically in one of many OO languages
(a) I and II only
(b) II and III only
(c) I, II, and III
(d) I only
Correct answer is (a)
Your score on this question is: 20.00
Feedback:
See section 3.3.2 of the course notes. See section 3.3.2 of the course notes.
1.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs that are directly connected to each other. The network performance has been found to be lacking, and an upgrade is planned. The computers are identical and place a comparable load on the network that is relatively constant and modest for each computer (in the order of 500 Kbps). What would you suggest for the upgrade?
(a) Replace the hubs with 100 Base-T hubs
(b) A new bank of dial-up modems
(c) Replace the hubs with 10 Base-T switches
(d) A small 10 Base-T switch to connect the existing hubs
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
2.
In a broadcast-based network, longer propagation delays
(a) do not affect the cost-benefit trade-off of carrier sensing
(b) significantly decrease the benefit of sensing the carrier before transmitting
(c) destroy the carrier, making it impossible to sense it before transmitting
(d) make it all the more critical to sense the carrier before transmitting
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.6 of the course notes.
--------------------------------------------------------------------------------
3.
Why do not all network switches use crossbars in their switching fabric?
For a given number of ports, crossbars are more expensive.
Crossbars are more likely to block connections unnecessarily between ports that are idle.
Crossbar designs are too simple.
(a) I and II only
(b) II and III only
(c) II only
(d) I only
Correct answer is (d)
Your score on this question is: 0.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
4.
In contrast to message switching, packet switching
needs to find a "copper" path to the receiver before transmitting any data
offers a better upper bound on transmission delay
suffers from greater overhead at the endpoints
(a) II and III only
(b) I and III only
(c) II only
(d) I and II only
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
5.
Which of the following are responsibilities of the data link layer?
Noticing transmission errors
Regulating transmission speed when a receiver is overwhelmed
Regulating transmission speed when any of several IP routers in a network path are overwhelmed
(a) I, II, and III
(b) II and III only
(c) I and II only
(d) I only
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
6.
A sender's data link layer uses "bit stuffing" to
(a) avoid confusing data bits with control bits
(b) mark the start and the end of a frame
(c) force the receiver to enlarge its flow control window
(d) pad the data so that it has an even length for parity calculations
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
7.
Which of the following statements most closely agrees with your position regarding the reliability of the service provided by the data link layer?
(a) The data link layer need not be concerned with reliability because the physical layer is perfectly reliable.
(b) The data link layer must provide connection-oriented service because it must retransmit lost data and eliminate duplicate data.
(c) The data link layer need not retransmit data, but must acknowledge received data because it must detect lost data.
(d) The data link layer's concern with reliability is an optimization, not a requirement.
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
8.
After the phone company installs a T1 trunk to an office building, which of the following can it provide to the tenants of the building? Recall that a T1 trunk has a capacity of 1.544 Mbps, and that a voice channel requires an isolated 3 KHz channel.
20 new telephone lines and a 200 Kbps digital data channel
A single 1.1 Mbps data channel
25 new telephone lines
(a) I, II, and III
(b) none
(c) I and II only
(d) II only
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
9.
A physical medium that uses the 4b/5b encoding scheme sends 5 bits for every 4 bits of data it needs to deliver. This encoding
decreases the maximum throughput of the medium
unnecessarily sends redundant data
improves the reliability of the transmission
(a) I and II only
(b) III only
(c) I and III only
(d) I, II, and III
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
10.
When a student in Hong Kong uses her computer to have a voice conversation with a teacher in Pittsburgh, the application she uses requires that the network deliver bits at a modest but constant bit rate. This is because, even though voice can be faithfully encoded in less than 64 Kbps, the late arrival of a voice sample produces a noticeable and unpleasant sound effect. Which of the following switching options will give you better quality?
(a) Packet-switched
(b) Circuit-switched
(c) Message-switched
(d) Space-switched
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
1.
In contrast with wireless communication, "wired" communication
does not suffer from attenuation and interference
can use any frequencies without a license
always has more throughput
(a) I and III only
(b) II only
(c) none
(d) I, II, and III
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
2.
After the phone company installs a T1 trunk to an office building, which of the following can it provide to the tenants of the building? Recall that a T1 trunk has a capacity of 1.544 Mbps, and that a voice channel requires an isolated 3 KHz channel.
20 new telephone lines and a 200 Kbps digital data channel
A single 1.1 Mbps data channel
25 new telephone lines
(a) none
(b) I, II, and III
(c) II only
(d) I and II only
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
3.
Radio stations are able to share the AM (Amplitude Modulation) spectrum by using _____ multiplexing
(a) wavelength-division
(b) frequency-division
(c) time-division
(d) phase shift
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
4.
When the data link layer applies "framing" to the data to be transmitted, it
(a) inserts flags to draw attention to high-priority data within a transmission
(b) adds the protocol headers from higher layers to the data before it transmits it
(c) cuts out the headers from higher layer protocols before transmission
(d) enhances it with extra data that permits the receiver to synchronize with the sender
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
5.
A fiber optic is found to be able to deliver light cleanly in a frequency range 25,000 GHz wide. This fiber can be used to create the following type of channel between two routers
a single 50 terabits per second (Tbps = 1,000 Gbps) data channel
5 2-Gbps data channels
one video channel but no data channels, because data cannot be encoded in light beams
(a) I and II only
(b) II only
(c) I only
(d) III only
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
6.
Collision Detection improves the throughput of multiple access networks because
it can shorten the length of garbled frames
it can decrease the number of garbled frames
it delays by a random amount of time when a collision is detected
(a) I, II, and III
(b) I only
(c) II and III only
(d) I and II only
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
7.
The maximum binary data throughput of a cable that cleanly transmits a range of frequencies up to 100 MHz is
(a) exactly 200 megabits per second
(b) exactly 200 megabytes per second
(c) currently 56 Kbps but more as modem technology improves
(d) within 80 and 120 megabits per second
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
8.
A specific CSMA-CD network such as 10-BASET "Ethernet"
(a) can connect very distant nodes
(b) suffers performance degradation as nodes are added
(c) works best for an even number of nodes
(d) has higher cost per node as nodes are added
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
9.
In a broadcast-based network, longer propagation delays
(a) make it all the more critical to sense the carrier before transmitting
(b) do not affect the cost-benefit trade-off of carrier sensing
(c) significantly decrease the benefit of sensing the carrier before transmitting
(d) destroy the carrier, making it impossible to sense it before transmitting
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.6 of the course notes.
--------------------------------------------------------------------------------
10.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs. The network performance has been found to be lacking, and an upgrade is planned. The computers usually have modest network needs (in the order of 500 Kbps), but one or two are occasionally used to receive high-quality remote video streams that require in the order of 10 Mbps. No more than two computers are used for this purpose at any given time, but any two may be used for this application. What would you suggest for the upgrade?
(a) A 10 Base-T bridge to connect several existing hubs
(b) Replace the hubs with 100 Base-T hubs
(c) A new bank of dial-up modems
(d) Replace the hubs with 10 Base-T switches
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
1.
Which of the following statements most closely agrees with your position regarding the reliability of the service provided by the data link layer?
(a) The data link layer's concern with reliability is an optimization, not a requirement.
(b) The data link layer need not retransmit data, but must acknowledge received data because it must detect lost data.
(c) The data link layer must provide connection-oriented service because it must retransmit lost data and eliminate duplicate data.
(d) The data link layer need not be concerned with reliability because the physical layer is perfectly reliable.
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
2.
A specific CSMA-CD network such as 10-BASET "Ethernet"
(a) suffers performance degradation as nodes are added
(b) can connect very distant nodes
(c) has higher cost per node as nodes are added
(d) works best for an even number of nodes
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
3.
In contrast to message switching, packet switching
needs to find a "copper" path to the receiver before transmitting any data
offers a better upper bound on transmission delay
suffers from greater overhead at the endpoints
(a) I and II only
(b) I and III only
(c) II only
(d) II and III only
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
4.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs. The network performance has been found to be lacking, and an upgrade is planned. The computers usually have modest network needs (in the order of 500 Kbps), but one or two are occasionally used to receive high-quality remote video streams that require in the order of 10 Mbps. No more than two computers are used for this purpose at any given time, but any two may be used for this application. What would you suggest for the upgrade?
(a) A 10 Base-T bridge to connect several existing hubs
(b) Replace the hubs with 10 Base-T switches
(c) A new bank of dial-up modems
(d) Replace the hubs with 100 Base-T hubs
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
5.
Why do not all network switches use crossbars in their switching fabric?
For a given number of ports, crossbars are more expensive.
Crossbars are more likely to block connections unnecessarily between ports that are idle.
Crossbar designs are too simple.
(a) II only
(b) I and II only
(c) II and III only
(d) I only
Correct answer is (d)
Your score on this question is: 0.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
6.
In a broadcast-based network, longer propagation delays
(a) significantly decrease the benefit of sensing the carrier before transmitting
(b) make it all the more critical to sense the carrier before transmitting
(c) do not affect the cost-benefit trade-off of carrier sensing
(d) destroy the carrier, making it impossible to sense it before transmitting
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.6 of the course notes.
--------------------------------------------------------------------------------
7.
If you have seen any mobile telephone antennas, you will have noticed that they have groups of radiating elements facing different directions. Most antennas we know are arranged in a triangle, so that each group spans a 120-degree arc of the horizon, but we have also seen squares in which each group spans a 90-degree arc instead. There is one such arrangement for each cell of a mobile phone system. This sort of base station is unsightly and expensive. A cell could instead use a single omnidirectional antenna that would be simple and inconspicuous. Why do you think the more complicated designs are used?
(a) To decrease the number of times a call must be handed off from one base station to another.
(b) To decrease frequency reuse without the need for time-division multiplexing
(c) To allow the use of switches based on space-division multiplexing
(d) To increase frequency reuse without having to build more antenna towers
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.6 of the course notes.
--------------------------------------------------------------------------------
8.
A cable is rated at 19200 baud. A 19200 baud cable is guaranteed to transmit a signal successfully that has the potential to change 19200 times per second. The maximum throughput of this cable, assuming a sensible encoding,
(a) can be any number greater than or equal to 19200 bits per second, depending on the way the data is encoded into signal voltages
(b) is exactly 19200 bits per second
(c) is between 19200 and 38400 bits per second, depending on the bit pattern of the transmitted data
(d) is less than 19200 bits per second
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
9.
After the phone company installs a T1 trunk to an office building, which of the following can it provide to the tenants of the building? Recall that a T1 trunk has a capacity of 1.544 Mbps, and that a voice channel requires an isolated 3 KHz channel.
20 new telephone lines and a 200 Kbps digital data channel
A single 1.1 Mbps data channel
25 new telephone lines
(a) none
(b) II only
(c) I and II only
(d) I, II, and III
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
10.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs that are directly connected to each other. The network performance has been found to be lacking, and an upgrade is planned. The computers are identical and place a comparable load on the network that is relatively constant and modest for each computer (in the order of 500 Kbps). What would you suggest for the upgrade?
(a) Replace the hubs with 10 Base-T switches
(b) A small 10 Base-T switch to connect the existing hubs
(c) A new bank of dial-up modems
(d) Replace the hubs with 100 Base-T hubs
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
1.
Why do not all network switches use crossbars in their switching fabric?
For a given number of ports, crossbars are more expensive.
Crossbars are more likely to block connections unnecessarily between ports that are idle.
Crossbar designs are too simple.
(a) II and III only
(b) II only
(c) I and II only
(d) I only
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
2.
In the year 2000, telephone and cable television companies are competing for the home Internet market. A typical offering of ADSL by the telephone companies is for a 1.5 Mbps link into the home, while a common offering by the cable television companies is for a shared 27 Mbps link into the home. The cost is usually comparable for these two options. Suppose you want to display the images at home that are constantly sent over the Internet by a security camera elsewhere. The camera has a relatively low refresh rate and the transmission will approximately require a constant 300 Kbps. Of course, you will also want to use your computer to surf the Internet. Which of the following would be valid arguments to get a cable modem instead of ADSL?
The cable modem always has better bandwidth and latency than ADSL.
The cable TV company has more experience transmitting analog video.
The camera is connected to the Internet via the same cable TV company
(a) I, II, and III
(b) III only
(c) I only
(d) I and III only
Correct answer is (b)
Your score on this question is: 0.00
Feedback:
See section 1.2.5 of the course notes.
--------------------------------------------------------------------------------
3.
After the phone company installs a T1 trunk to an office building, which of the following can it provide to the tenants of the building? Recall that a T1 trunk has a capacity of 1.544 Mbps, and that a voice channel requires an isolated 3 KHz channel.
20 new telephone lines and a 200 Kbps digital data channel
A single 1.1 Mbps data channel
25 new telephone lines
(a) I, II, and III
(b) I and II only
(c) none
(d) II only
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
4.
Collision Detection improves the throughput of multiple access networks because
it can shorten the length of garbled frames
it can decrease the number of garbled frames
it delays by a random amount of time when a collision is detected
(a) I, II, and III
(b) II and III only
(c) I and II only
(d) I only
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
5.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs. The network performance has been found to be lacking, and an upgrade is planned. The computers usually have modest network needs (in the order of 500 Kbps), but one or two are occasionally used to receive high-quality remote video streams that require in the order of 10 Mbps. No more than two computers are used for this purpose at any given time, but any two may be used for this application. What would you suggest for the upgrade?
(a) Replace the hubs with 100 Base-T hubs
(b) Replace the hubs with 10 Base-T switches
(c) A 10 Base-T bridge to connect several existing hubs
(d) A new bank of dial-up modems
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.4 of the course notes.
--------------------------------------------------------------------------------
6.
A sender's data link layer uses "bit stuffing" to
(a) mark the start and the end of a frame
(b) force the receiver to enlarge its flow control window
(c) avoid confusing data bits with control bits
(d) pad the data so that it has an even length for parity calculations
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
7.
In a broadcast-based network, longer propagation delays
(a) make it all the more critical to sense the carrier before transmitting
(b) do not affect the cost-benefit trade-off of carrier sensing
(c) significantly decrease the benefit of sensing the carrier before transmitting
(d) destroy the carrier, making it impossible to sense it before transmitting
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.6 of the course notes.
--------------------------------------------------------------------------------
8.
In contrast to message switching, packet switching
needs to find a "copper" path to the receiver before transmitting any data
offers a better upper bound on transmission delay
suffers from greater overhead at the endpoints
(a) II and III only
(b) I and II only
(c) I and III only
(d) II only
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
9.
A parity code is a(n)
(a) duplex transmission technique
(b) error-correcting code
(c) error-detecting code
(d) fair resource allocation scheme
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
10.
A fiber optic is found to be able to deliver light cleanly in a frequency range 25,000 GHz wide. This fiber can be used to create the following type of channel between two routers
a single 50 terabits per second (Tbps = 1,000 Gbps) data channel
5 2-Gbps data channels
one video channel but no data channels, because data cannot be encoded in light beams
(a) II only
(b) III only
(c) I and II only
(d) I only
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
1.
Which of the following statements most closely agrees with your position regarding the reliability of the service provided by the data link layer?
(a) The data link layer must provide connection-oriented service because it must retransmit lost data and eliminate duplicate data.
(b) The data link layer need not retransmit data, but must acknowledge received data because it must detect lost data.
(c) The data link layer need not be concerned with reliability because the physical layer is perfectly reliable.
(d) The data link layer's concern with reliability is an optimization, not a requirement.
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
2.
In the year 2000, telephone and cable television companies are competing for the home Internet market. A typical offering of ADSL by the telephone companies is for a 1.5 Mbps link into the home, while a common offering by the cable television companies is for a shared 27 Mbps link into the home. The cost is usually comparable for these two options. Suppose you want to display the images at home that are constantly sent over the Internet by a security camera elsewhere. The camera has a relatively low refresh rate and the transmission will approximately require a constant 300 Kbps. Of course, you will also want to use your computer to surf the Internet. Which of the following would be valid arguments to get a cable modem instead of ADSL?
The cable modem always has better bandwidth and latency than ADSL.
The cable TV company has more experience transmitting analog video.
The camera is connected to the Internet via the same cable TV company
(a) I only
(b) I, II, and III
(c) III only
(d) I and III only
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.5 of the course notes.
--------------------------------------------------------------------------------
3.
When a student in Hong Kong uses her computer to have a voice conversation with a teacher in Pittsburgh, the application she uses requires that the network deliver bits at a modest but constant bit rate. This is because, even though voice can be faithfully encoded in less than 64 Kbps, the late arrival of a voice sample produces a noticeable and unpleasant sound effect. Which of the following switching options will give you better quality?
(a) Message-switched
(b) Space-switched
(c) Packet-switched
(d) Circuit-switched
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
4.
A cable is rated at 19200 baud. A 19200 baud cable is guaranteed to transmit a signal successfully that has the potential to change 19200 times per second. The maximum throughput of this cable, assuming a sensible encoding,
(a) can be any number greater than or equal to 19200 bits per second, depending on the way the data is encoded into signal voltages
(b) is between 19200 and 38400 bits per second, depending on the bit pattern of the transmitted data
(c) is exactly 19200 bits per second
(d) is less than 19200 bits per second
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
5.
A packet-switched network uses switches that schedule packets using a first-in-first-out (FIFO) discipline. Several people want to carry out a conference over this network. The conference is carried out via typed text for the most part, but, occasionally, one of the parties has to send a large video. This happens very rarely. Which of the following switching approaches is most suitable for this application?
(a) Circuit-switched
(b) Space-switched
(c) Packet-switched
(d) Message-switched
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
6.
Why do not all network switches use crossbars in their switching fabric?
For a given number of ports, crossbars are more expensive.
Crossbars are more likely to block connections unnecessarily between ports that are idle.
Crossbar designs are too simple.
(a) I and II only
(b) I only
(c) II only
(d) II and III only
Correct answer is (b)
Your score on this question is: 10.00
Feedback:
See section 1.2.3 of the course notes.
--------------------------------------------------------------------------------
7.
The maximum binary data throughput of a cable that cleanly transmits a range of frequencies up to 100 MHz is
(a) currently 56 Kbps but more as modem technology improves
(b) within 80 and 120 megabits per second
(c) exactly 200 megabytes per second
(d) exactly 200 megabits per second
Correct answer is (d)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
8.
Radio stations are able to share the AM (Amplitude Modulation) spectrum by using _____ multiplexing
(a) time-division
(b) phase shift
(c) frequency-division
(d) wavelength-division
Correct answer is (c)
Your score on this question is: 10.00
Feedback:
See section 1.2.1 of the course notes.
--------------------------------------------------------------------------------
9.
What is the type of an "8+1" parity code that outputs 100101011?
(a) Odd Parity
(b) Even Parity
(c) Null Parity
(d) Cannot tell since we do not know which bit is the parity bit
Correct answer is (a)
Your score on this question is: 10.00
Feedback:
See section 1.2.2 of the course notes.
--------------------------------------------------------------------------------
10.
A university has 20 computers in a laboratory that is currently served by several small 10 Base-T "Ethernet" hubs that are directly connected to each other. The network performance has been found to be lacking, and an upgrade is planned. The computers are identical and place a comparable load on the network that is relatively constant and modest for each computer (in the order of 500 Kbps). What would you suggest for the upgrade?
(a) Replace the hubs with 10 Base-T switches
(b) Replace the hubs with 100 Base-T hubs
(c) A small 10 Base-T switch to connect the existing hubs
(d) A new bank of dial-up modems