SSD8 All Muti Choice

1

7.While writing a small application that downloads a program from one of several Web sites, you realize that you would like to download the program from the server that has the best connection to the computer in which the downloader executes. You have no access to the servers, so you cannot change their networking software or install new services, but you can incorporate any code you want into the downloader application. Which tool's source code will you look at for inspiration, assuming you want to minimize the execution time of your program?

(a) Netperf

(b) Ping

(c) Netstat

(d) Traceroute

Correct answer is (b)

Your score on this question is:0.00

1.

Which of the following parameters can be specified in the header of a request in the Hypertext Transfer Protocol (HTTP)?

The types of image formats that a browser understands

The type of browser (e.g., Netscape, Internet Explorer) making the request

The method by which the request is to be satisfiedfor example, whether the request is a GET of a form submission

(a) III only

(b) I, II, and III

(c) II and III only

(d) I and II only


Your score on this question is: 0.00

Feedback:

See section 1.1.1 of the course notes.

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2.

Which of the following distinguish stream sockets (e.g., TCP) from datagram sockets (e.g., UDP)?

Stream sockets guarantee delivery of the data sent through them.

Stream sockets can be used to send application data to a remote host, whereas datagram sockets can only send control commands.

Stream sockets have greater overhead.

(a) I and III only

(b) I and II only

(c) II and III only

(d) I only

Correct answer is (a)


Feedback:


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3.

A computer sends 100 Kbytes of aggregate data to another computer through the network. If this transmission time takes 10 seconds and setup time is negligible, the throughput of this network is

(a) not able to be determined with the information given

(b) exactly 10 Kbps

(c) in the range from 60 to 120 Kbps (kilobits per second)

(d) in the range from 6 to 12 Kbps (kilobits per second)

Correct answer is (c)


Feedback:


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4.

An application on a computer sends data through a socket to another computer. Which of the following are specified by the communication protocol?

The contents of the message body

The speed of transmission

The header format, which specifies the header field sizes and meanings

(a) II and III only

(b) III only

(c) I only

(d) I and III only



Feedback:


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5.

An advantage of defining network protocols through agreement among many companies and individuals is that

(a) different implementations can then communicate with each other

(b) otherwise source code would need to be shipped with all networking applications

(c) only one implementation need then be created

(d) a protocol designed by committee always has better performance than that designed by a single company or research project



Feedback:


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6.

We send a packet from host A to host B, which immediately acknowledges it. We measure the interval between the time the packet is sent by A and its acknowledgement is received. This interval is found to be 180 milliseconds. What can be said about the latency of the link from A to B?

(a) It is smaller than 180 ms.

(b) It is greater than 180 ms.

(c) It is exactly 180 ms.

(d) It is exactly 90 ms.



Feedback:


(d) This would be so only if the latency in the direction A->B was identical to the latency in the direction B->A

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7.

What can be said about the protocol used by the implementation of the transport layer of an Internet host?

It guarantees delivery.

It is the Transmission Control Protocol (TCP).

It uses services provided by the session layer.

(a) none

(b) I only

(c) I and II only

(d) I and III only



Feedback:


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8.

Which of the following methods are invoked by a client implemented with sockets?

connect( )

listen( )

read( )

(a) I, II, and III

(b) III only

(c) I only

(d) I and III only

Correct answer is (d)


Feedback:


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9.

When you connect your computer to the Internet, the protocol(s) your computer uses is (are) selected according to

(a) the application client and server you use at each moment

(b) which HTTP (Web) server you connect to

(c) which operating system is running on your computer

(d) what vendor your Internet service provider purchased equipment from



Feedback:


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10.

Which of the following activities use an inter-network?

A phone call from Pittsburgh in the United States to Chennai in India

A phone call from a wired phone to a mobile ("cell") phone

A chat session between two computers connected to an office Ethernet

(a) I, II, and III

(b) I only

(c) I and II only

(d) III only



Feedback:


1.


(a) only one implementation need then be created

(b) a protocol designed by committee always has better performance than that designed by a single company or research project

(c) otherwise source code would need to be shipped with all networking applications

(d) different implementations can then communicate with each other



Feedback:


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2.

Packet collisions occur in an Ethernet network because

(a) the Ethernet switching mechanism may occasionally send two packets through the same route

(b) two different Ethernet networks may be spliced together

(c) two Ethernet nodes can send packets at the same time

(d) the Ethernet uses a ring topology



Feedback:


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3.

The Maximum Transfer Unit (MTU) is a parameter of

(a) the technology of the physical network

(b) the application protocol

(c) the size of data sent by the application

(d) the operating system



Feedback:


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4.

Two packets A and B are sent in that order through a connectionless communication network. They will arrive at the destination

(a) in the order A-B, after possibly having traversed different routes

(b) in the order A-B, after having traversed the same route

(c) in any order, after having traversed the same route

(d) in any order, after possibly having traversed different routes



Feedback:


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5.

Ethernet (IEEE 802.3) is an example of

(a) a successful example of the Internet's strategy of developing standards through "rough consensus and running code"

(b) an a priori standard

(c) a de facto standard later developed into a de jure standard

(d) a standard developed by the International Telecommunications Union



Feedback:


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6.

In a broadcast network

(a) only the destination computer sees a packet

(b) only the computers that are tuned to a channel see and process the packets in that channel

(c) all computers see and process the application data within all packets

(d) all computers see all packets, but the application data in each packet is only processed by the destination computer



Feedback:


(b) A network with channels would be, in effect, multiple broadcast networks.

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7.

The transmission of high-quality, interactive voice and video over the current Internet is difficult because today's Internet

(a) gives higher priority to bulk data transfers

(b) is unable to guarantee minimum throughput or maximum latency for a given connection

(c) does not really have sufficient throughput

(d) uses connectionless protocols



Feedback:


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8.

What can be said concerning the protocol that is used by the implementation of the network layer of an Internet host?


It is the Internet Protocol (IP).


(a) none

(b) I and II only

(c) I only

(d) II only



Feedback:


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9.


(a) exactly 10 Kbps

(b) in the range from 60 to 120 Kbps (kilobits per second)

(c) not able to be determined with the information given

(d) in the range from 6 to 12 Kbps (kilobits per second)



Feedback:


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10.

Why do network applications send "messages," but the network transmits information in "packets?"

Buffer allocation and error handling is easier when done for smaller chunks of data.

Multiple messages can be sent in a single large packet to decrease overhead.

Network engineers and application programmers just use different terminology for the same unit of application data.

A message needs to be packaged with the instructions to process it at the destination.

(a) II and IV only

(b) II and III only

(c) I and II only

(d) I, II, III, and IV



Feedback:


1.


(a) different implementations can then communicate with each other

(b) only one implementation need then be created

(c) otherwise source code would need to be shipped with all networking applications

(d) a protocol designed by committee always has better performance than that designed by a single company or research project



Feedback:


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2.

The Protocol Data Unit (PDU) that is sent by a protocol layer to its peer on the destination system typically includes

A payload

A protocol header

A router vendor ID

(a) II only

(b) I and III only

(c) I, II, and III

(d) I and II only



Feedback:


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3.

How does an operating system identify the application to which data coming in from the network should be relayed?

(a) By the file extension of the data

(b) Only one application at a time is given access to the network.

(c) By the protocol with which the data was sent

(d) By the port number carried by the transport protocol



Feedback:


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4.





(a) I only

(b) I and III only

(c) I and II only

(d) II and III only



Feedback:


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5.






(a) I and II only

(b) II and IV only

(c) I, II, III, and IV

(d) II and III only



Feedback:


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6.


(a) exactly 10 Kbps

(b) in the range from 6 to 12 Kbps (kilobits per second)

(c) in the range from 60 to 120 Kbps (kilobits per second)

(d) not able to be determined with the information given



Feedback:


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7.


(a) the operating system

(b) the technology of the physical network

(c) the size of data sent by the application

(d) the application protocol



Feedback:


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8.



(b) the Ethernet uses a ring topology

(c) two Ethernet nodes can send packets at the same time

(d) two different Ethernet networks may be spliced together



Feedback:


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9.

What can be said about the protocol used by the implementation of the transport layer of an Internet host?


It is the Transmission Control Protocol (TCP).


(a) none

(b) I only

(c) I and III only

(d) I and II only



Feedback:


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10.

Which of the following methods are invoked by a server implemented with sockets?

connect( )

listen( )

accept( )

(a) I, II, and III

(b) II and III only

(c) II only

(d) III only



Feedback:


1.

In contrast to standards developed by traditional standards organizations like the International Telecommunications Union (ITU) or the International Standards Organization (ISO), standards developed by the Internet Engineering Task Force (IETF) can be

(a) modified arbitrarily by the Advance Research projects Agency (ARPA) of the United States Department of Defense, which originally developed the Internet

(b) applied before they have been embodied in working implementations, in order not to delay progress

(c) developed in secret by the members of the IETF until the standards mature sufficiently to withstand public criticism

(d) extensively critiqued and modified by individuals, without requiring them to have special membership status



Feedback:


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2.

John is using his bank's Web server to pay his telephone bill electronically. Which kind(s) of network interaction take(s) place in this Scenario, from the moment John logs into his bank's Web site until the telephone company receives the money?

People-people

People-computer

Computer-computer

(a) III only

(b) I, II, and III

(c) II only

(d) II and III only



Feedback:

See section 1.1 of the course notes.

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3.





(a) III only

(b) I only

(c) I and II only

(d) I, II, and III



Feedback:


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4.

A packet with no data is sent from host A to host B on an otherwise idle network. The packet is found to have taken 35 milliseconds to reach B. The incremental overhead to send an additional byte (usually called the "throughput") is estimated to be five microseconds by repeatedly measuring the transmission times of long packets. Approximately, how long will an eight Kbytes (8192 bytes) packet take to reach B when sent from A?

(a) 76 milliseconds

(b) 40 milliseconds

(c) 55 milliseconds

(d) cannot be determined from the information given



Feedback:


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5.

Two packets A and B are sent in that order through a connection-oriented communication network. They could arrive at the destination

(a) only in the order A-B, after having traversed the same route

(b) only in the order A-B, after possibly having traversed different routes

(c) in any order, after having traversed the same route




Feedback:


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6.

The throughput of a network link for an HTTP session is measured in two ways. Measurement A is the total amount of data received by the browser, divided by the duration of the session. Measurement B is the total amount of data received by the operating system on behalf of the browser, divided by the duration of the session. Which of the following statements about A and B is true?

(a) A is smaller than B

(b) B is equal to A

(c) B and A are not related

(d) B is smaller than A



Feedback:


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7.

What can be said concerning the protocol that is used by the implementation of the network layer of an Internet host?


It is the Internet Protocol (IP).


(a) none

(b) I only

(c) I and II only

(d) II only



Feedback:


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8.

The Internet received its name in the 1980s because

(a) it consisted of many interconnected networks

(b) it was meant to be a network internal to the United States Department of Defense

(c) it achieved international scope with the addition of the City University of London

(d) it was an interim (temporary) design of what it later became, but the name stuck



Feedback:


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9.


connect( )

listen( )

accept( )

(a) I, II, and III

(b) III only

(c) II and III only

(d) II only



Feedback:


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10.

In a broadcast network

(a) only the destination computer sees a packet

(b) all computers see all packets, but the application data in each packet is only processed by the destination computer

(c) only the computers that are tuned to a channel see and process the packets in that channel

(d) all computers see and process the application data within all packets



Feedback:


1.

Every Protocol Data Unit (PDU) that is sent by a protocol layer to its remote peer on the destination system always includes:

The headers for all the protocols of the layers above it

The headers for the protocol of the layer below it

Application Data

(a) I, II, and III

(b) I and III only

(c) III only

(d) None



Feedback:


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2.


(a) only in the order A-B, after possibly having traversed different routes

(b) in any order, after having traversed the same route

(c) in any order, after possibly having traversed different routes

(d) only in the order A-B, after having traversed the same route



Feedback:


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3.

When you connect your computer to the Internet, the protocol(s) your computer uses is (are) selected according to

(a) what vendor your Internet service provider purchased equipment from

(b) which operating system is running on your computer

(c) which HTTP (Web) server you connect to

(d) the application client and server you use at each moment



Feedback:


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4.

How does an operating system identify the application to which data coming in from the network should be relayed?

(a) By the file extension of the data

(b) By the port number carried by the transport protocol

(c) By the protocol with which the data was sent

(d) Only one application at a time is given access to the network.



Feedback:


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5.

You have recently become the first network engineer of a large corporation with offices worldwide. The company is considering the installation of a data network, but the Board of Directors is rather old-fashioned and does not see the need to change the company's time-honored business practices. Your first task at the job is to justify your salary and the cost of a new network, and for this purpose you are about to give a presentation to the Board of Directors. Which of the following would you include in your presentation? Assume the directors are extremely intelligent, though perhaps not knowledgeable in your field.

Lower expenditures on computer hardware

Higher availability of customer services

Better protection of the company's proprietary information

(a) I and II only

(b) I and III only

(c) II and III

(d) II only



Feedback:


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6.


connect( )

listen( )

accept( )

(a) II and III only

(b) II only

(c) I, II, and III

(d) III only



Feedback:


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7.





(a) III only

(b) I and II only

(c) I only

(d) I, II, and III



Feedback:


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8.


(a) an a priori standard

(b) a de facto standard later developed into a de jure standard

(c) a successful example of the Internet's strategy of developing standards through "rough consensus and running code"

(d) a standard developed by the International Telecommunications Union



Feedback:


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9.



(b) the Ethernet uses a ring topology

(c) two different Ethernet networks may be spliced together

(d) two Ethernet nodes can send packets at the same time



Feedback:


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10.


(a) 76 milliseconds

(b) cannot be determined from the information given

(c) 40 milliseconds

(d) 55 milliseconds



Feedback:


1.





(a) I and III only

(b) I only

(c) II and III only

(d) I and II only



Feedback:


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2.


(a) a standard developed by the International Telecommunications Union

(b) a successful example of the Internet's strategy of developing standards through "rough consensus and running code"

(c) an a priori standard

(d) a de facto standard later developed into a de jure standard



Feedback:


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3.

The Internet received its name in the 1980s because

(a) it consisted of many interconnected networks

(b) it was an interim (temporary) design of what it later became, but the name stuck

(c) it achieved international scope with the addition of the City University of London

(d) it was meant to be a network internal to the United States Department of Defense



Feedback:


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4.

Which of the following are specified by the HTTP protocol?

The syntax of the request header

The syntax of the response header

The specific legal names of the request header fields

(a) I and II only

(b) I and III only

(c) I only

(d) I, II, and III



Feedback:


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5.

Two packets A and B are sent in that order through a connectionless communication network. They will arrive at the destination

(a) in any order, after possibly having traversed different routes

(b) in the order A-B, after having traversed the same route

(c) in the order A-B, after possibly having traversed different routes

(d) in any order, after having traversed the same route



Feedback:


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6.


(a) the application protocol

(b) the technology of the physical network

(c) the operating system

(d) the size of data sent by the application



Feedback:


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7.


(a) 40 milliseconds

(b) 76 milliseconds

(c) 55 milliseconds

(d) cannot be determined from the information given



Feedback:


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8.


(a) only in the order A-B, after having traversed the same route

(b) in any order, after having traversed the same route

(c) only in the order A-B, after possibly having traversed different routes




Feedback:


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9.






(a) II and III only

(b) I, II, III, and IV

(c) II and IV only

(d) I and II only



Feedback:


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10.

An application on a computer sends data through a socket to another computer. Which of the following are specified by the communication protocol?

The contents of the message body

The speed of transmission

The header format, which specifies the header field sizes and meanings

(a) III only

(b) I and III only

(c) I only

(d) II and III only



Feedback:


(b) The protocol specifies how to transmit the contents, but not what the contents are.

1.

Which of the following functions can the transport layer provide to applications?

End-to-end flow control

Packet forwarding

Congestion control

(a) I only

(b) I and III only

(c) II and III only

(d) I, II, and III



Feedback:


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2.

The Pittsburgh Supercomputing Center and the San Diego Supercomputing Center are linked to the Internet via very high-speed lines (in 1999, about 622 Mbps). Separated by about 4,000 Km, and several routers, the network installers measured the round trip time between these two sites to be about 50 milliseconds. You want to exchange a large data set between two very fast computers at these sites. The physical network capacity and/or speed of the computers limit the maximum TCP throughput to be about 50 million bytes per second under ideal circumstances. Assuming the channel is free of interference and that very few packets, if any, are dropped, how much memory would you allocate for a TCP connection at the sender in order to maximize throughput without spending money unnecessarily?

(a) none

(b) as much as possible

(c) a few megabytes

(d) a few kilobytes, enough to hold one packet and one acknowledgment



Feedback:


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3.

You have just written an implementation of a transport protocol. You have aggressively pursued performance. For example, all acknowledgments are piggybacked on top of regular data packets, in order to minimize their overhead. When your company releases your product, however, you get the following complaint:

(a) Many packets are retransmitted many times even though the network is idle.

(b) ARP responses take a lot longer than before.

(c) Packet headers have doubled in size, thereby halving the expected performance gains.

(d) Many more packets than before fail to reach the receiving host.



Feedback:


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4.

What is the service that TCP provides but UDP does not?

(a) Error detection using checksum

(b) API provided to application layer

(c) Addressing

(d) Congestion control



Feedback:


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5.

A transport protocol entity determines that the underlying network is able to deliver 100 of its packets every second. Each of these packets contains 1,500 bytes (including transport headers). In addition, the time elapsed between the transmission of a packet and the reception of its acknowledgement is 3 seconds on the average. An efficient and smooth flow would require that the sliding window size be no less than approximately

(a) 300 packets

(b) 34 packets

(c) 600 packets

(d) 100 packets



Feedback:


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6.

The load offered to a network is the aggregate data rate at which the hosts connected to it attempt to send data. When the offered load increases by 20%, the amount of data successfully transported

may decrease by more than 30%

may decrease by less than 30%

may increase by less than 30%

(a) I, II, and III

(b) II and III only

(c) III only

(d) I and II only



Feedback:


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7.

TCP provides reliability in the presence of packet losses by

(a) congestion control

(b) acknowledgment timeouts

(c) end-to-end flow control

(d) multiple routes for each packet



Feedback:

When an expected acknowledgment has not arrived within a time period, a packet is retransmitted, on the assumption that the data packet was lost. See section 2.1.3 of the course notes.

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8.

A surveillance camera is connected to a computer that sends video frames to a remote site where multiple such cameras are monitored. The video stream uses the TCP transport protocol. When the network experiences congestion

the receiver should adjust the frame playback rate

the sender should adjust the frame capture rate

TCP automatically adjusts the video frame transmission rate

(a) I, II, and III

(b) II only

(c) I and II only

(d) III only



Feedback:


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9.

The Pittsburgh Supercomputing Center and the San Diego Supercomputing Center are linked to the Internet via very high-speed lines (in 1999, about 622 Mbps). Separated by about 4,000 Km and several routers, the network installers measured the round trip time between these two sites to be about 50 milliseconds. You want to exchange a large data set between two very fast computers at these sites. The physical network capacity and/or speed of the computers limit the maximum TCP throughput to be about 50 million bytes per second under ideal circumstances. The operating system of the sending computer has allocated 500 Kbytes to the TCP protocol that manages the exchange. The systems administrator then increases this allocation to 2.5 Mbytes. Which of the following are certain to ensue?

Throughput increases

Sender's transmission window grows

Receiver's transmission window shrinks

(a) I and II only

(b) I, II, and III

(c) II only

(d) none



Feedback:

The window size may be constrained by congestion, not merely by the capacity of the two hosts involved. The sending host might already be consuming much less than the initially allocated 500 Kbytes. See section 2.1.4 of the course notes.

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10.

The Transmission Control Protocol (TCP) differs from the User Data Protocol (UDP) in that

TCP is connection-oriented

TCP needs to manage buffer space

TCP addresses are a pair (IP address, port number)

(a) III only

(b) I, II, and III

(c) I only

(d) I and II only



Feedback:


1.

You are charged with setting up the technology required to transmit a video-conference over an IP-based internetwork. You will have to implement a sending and a receiving application. Where will you handle network congestion?

(a) In the sending application only

(b) In neither the sending nor receiving application, because late-arriving video frames are of no use

(c) In neither the sending nor receiving application, because TCP takes care of it

(d) In both the sending and receiving applications



Feedback:


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2.

In today's Internet, a TCP address is

(a) a 32-bit integer and a process number

(b) a 32-bit integer and a "port" number

(c) a 32-bit integer and an application name



Feedback:


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3.

A TCP implementation that uses a sliding window for flow control has a coding error that causes it to calculate a window size greater than the ideal. What are some of the likely effects of this error?

Unnecessarily idle network links

Unnecessary packet losses

Greater memory usage in routers

(a) II only

(b) I, II, and III

(c) II and III only

(d) I only



Feedback:


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4.

Computer A has just received a TCP segment with a header that has the values 1500 and 1501 in the ACK and sequence number fields, respectively, from computer B. From this, we know that computer B is waiting for sequence number

(a) 1501

(b) 1500

(c) 1499

(d) 1502



Feedback:


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5.

Which of the following functions can the transport layer provide to applications?

End-to-end flow control

Packet forwarding

Congestion control

(a) II and III only

(b) I, II, and III

(c) I only

(d) I and III only



Feedback:


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6.

Most postal systems allow customers to request a receipt notification, by which the Postal Service promises to notify the sender when the letter has been delivered to the recipient. This makes the postal system

a reliable network services provider

a reliable transport services provider

a datagram network service provider

(a) II only

(b) III only

(c) I and III only

(d) I only



Feedback:


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7.


(a) 600 packets

(b) 34 packets

(c) 100 packets

(d) 300 packets



Feedback:


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8.

A 4-port Internet router has been designed with enough buffer space and CPU power to service its four links at their maximum capacity. Which of the following is(are) sufficient to keep the router from becoming congested?

Neighboring routers are similarly designed.

All ports have comparable throughput and latency.

Links to other routers have neither interference nor any losses.

(a) II and III only

(b) none

(c) I and II only

(d) I, II, and III



Feedback:


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9.

TCP packets may be lost

when the sender runs out of buffer space

when a router runs out of buffer space

when the subnet, running IP, is congested

(a) II and III only

(b) I, II, and III

(c) III only

(d) II only



Feedback:


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10.

The Pittsburgh Supercomputing Center and the San Diego Supercomputing Center are linked to the Internet via very high-speed lines (in 1999, about 622 Mbps). Separated by about 4,000 Km, and several routers, the network installers measured the round trip time between these two sites to be about 50 milliseconds. You want to exchange a large data set between two very fast computers at these sites. The physical network capacity and/or speed of the computers limit the maximum TCP throughput to be about 50 million bytes per second under ideal circumstances. Assuming the channel is free of interference and that very few packets, if any, are dropped, how much memory would you allocate for a TCP connection at the sender in order to maximize throughput without spending money unnecessarily?

(a) a few kilobytes, enough to hold one packet and one acknowledgment

(b) a few megabytes

(c) as much as possible

(d) none



Feedback:


1.

A surveillance camera is connected to a computer that sends video frames to a remote site where multiple such cameras are monitored. The video stream uses the TCP transport protocol. When the network experiences congestion

the receiver should adjust the frame playback rate

the sender should adjust the frame capture rate

TCP automatically adjusts the video frame transmission rate

(a) I, II, and III

(b) I and II only

(c) III only

(d) II only



Feedback:


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2.

Which of the following apply to the transport protocol (e.g., TCP) but not to the network-layer protocol (e.g., IP)?

It need not be connection-oriented.

It cannot guarantee, by itself, that data is received completely and without errors.

It is only executed at the sender and receiver, not within the network infrastructure of routers and switches.

(a) II and III only

(b) I and II only

(c) II only

(d) III only



Feedback:


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3.





(a) I, II, and III

(b) III only

(c) I and II only

(d) II and III only



Feedback:


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4.

Most postal systems provide a "COD" service, by which the recipient pays for goods when she picks them up at the post office. For the sender and seller, this incurs a delay in payment between the time the goods are sent and the time the post office returns the customer's payment. In a sense, during this period, the seller is loaning money to the buyer. To limit its credit liability, the seller typically limits the number of COD packages that are outstanding to a particular customer. This means that after ordering N items, the customer may be unable to order any more until at least one of the N items has arrived and been paid for. What would you call N now that you are a networking expert?

(a) Maximum Transfer Unit (MTU)

(b) Retransmit timeout

(c) Sliding window size

(d) Store-and-forward buffer



Feedback:


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5.



(b) Packet headers have doubled in size, thereby halving the expected performance gains.

(c) ARP responses take a lot longer than before.

(d) Many more packets than before fail to reach the receiving host.



Feedback:


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6.

In designing a network protocol stack, the end-to-end argument would suggest that

(a) a feature should be implemented in as low a layer as possible

(b) all network devices should support all protocols

(c) each endpoint in a connection is a peer in the protocol

(d) a feature should be implemented in as high a layer as possible



Feedback:


(c) While true, this is not the end-to-point argument

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7.


(a) 1502

(b) 1499

(c) 1501

(d) 1500



Feedback:


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8.

Two programs execute in different computers and communicate through a TCP connection. Which of the following is certain when an IP packet supporting this connection successfully reaches the network interface of the receiving host?

Its payload data will be delivered to the receiving process.

An acknowledgment will be issued from the receiving to the sending computer.

The sending host will move its sliding window forward.

(a) II and III only

(b) II only

(c) I, II, and III

(d) none



Feedback:


(c) The acknowledgment may fail to reach the sending computer, in which case the data will not be delivered.

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9.

In today's Internet, a TCP address is

(a) a 32-bit integer and a "port" number

(b) a 32-bit integer and an application name

(c) a 32-bit integer and a process number



Feedback:


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10.





(a) II and III only

(b) II only

(c) I, II, and III

(d) III only



Feedback:


1.

You are charged with setting up the technology required to transmit a video-conference over an IP-based internetwork. You will have to implement a sending and a receiving application. Where will you handle network congestion?

(a) In neither the sending nor receiving application, because late-arriving video frames are of no use

(b) In both the sending and receiving applications

(c) In the sending application only

(d) In neither the sending nor receiving application, because TCP takes care of it



Feedback:


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2.

An open-loop approach to network congestion may

drop packets

deny connection requests

dynamically adapt to network conditions

(a) I and III only

(b) I and II only

(c) III only

(d) none



Feedback:


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3.


(a) 300 packets

(b) 100 packets

(c) 600 packets

(d) 34 packets



Feedback:


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4.

In a network that is mostly used for HTTP (Web) traffic, which of the following is a reasonable approach to minimizing the amount of wasted bandwidth?

(a) Populate routers with more memory than they will ever need.

(b) Have data sources send data as soon as it is available.

(c) Have data sources increase their sending rate until congestion is detected.

(d) Divide the available bandwidth equally among all connections.



Feedback:


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5.





(a) II only

(b) I, II, and III

(c) III only

(d) II and III only



Feedback:


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6.

An open-loop congestion prevention strategy that successfully prevents congestion in all circumstances

(a) piggybacks several acknowledgments into data traffic

(b) wastes available bandwidth

(c) changes packet timeouts depending on network conditions

(d) discards packets that arrive before packets with lower sequence numbers



Feedback:


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7.





(a) I and II only

(b) II and III only

(c) II only

(d) III only



Feedback:


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8.


(a) Addressing

(b) API provided to application layer

(c) Error detection using checksum




Feedback:


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9.

Most postal systems allow customers to request a receipt notification, by which the Postal Service promises to notify the sender when the letter has been delivered to the recipient. This makes the postal system

a reliable network services provider

a reliable transport services provider

a datagram network service provider

(a) II only

(b) I only

(c) I and III only

(d) III only



Feedback:


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10.





(a) I and II only

(b) III only

(c) II and III only

(d) I, II, and III



Feedback:


1.



(b) Packet headers have doubled in size, thereby halving the expected performance gains.

(c) Many more packets than before fail to reach the receiving host.

(d) ARP responses take a lot longer than before.



Feedback:


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2.

The router designers of a well-known network equipment manufacturer are having an internal debate. Some of them want to add reliability to the network-layer protocol, because they have devised a way to do this without making the routers any more costly. Their manager likes this, because it will give the marketing department a powerful weapon in promoting the company's products. The manager has hired you to enumerate the technical benefits of the proposal. Which of the following does your list include?

Early detection and recovery of data loss and corruption

Better service to multi-media traffic

Elimination of TCP from routers

(a) I only

(b) II only

(c) I, II, and III

(d) III only



Feedback:


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3.

Two programs execute in different computers and communicate through a TCP connection. Which of the following is certain when an IP packet supporting this connection successfully reaches the network interface of the receiving host?

Its payload data will be delivered to the receiving process.

An acknowledgment will be issued from the receiving to the sending computer.

The sending host will move its sliding window forward.

(a) I, II, and III

(b) II and III only

(c) none

(d) II only



Feedback:


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4.


TCP is connection-oriented

TCP needs to manage buffer space

TCP addresses are a pair (IP address, port number)

(a) III only

(b) I only

(c) I and II only

(d) I, II, and III



Feedback:


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5.

A TCP implementation that uses a sliding window for flow control has a coding error that causes it to calculate a window size smaller than the ideal. What are some of the likely effects of this error?




(a) II only

(b) II and III only

(c) I, II, and III

(d) I only



Feedback:


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6.

A new telephone company has approached your Internet provider's backbone operator with a new, flexible billing scheme. The phone company will periodically increase the capacity of the links needed by the backbone, at a price. The periodic increase will occur when the links are saturated beyond some threshold. This would be implemented by checking the network status every 10 minutes, and adjusting capacity if needed. The manager at your ISP is very happy about this, because it will entail which of the following?

No congestion ever again

Crystal-clear audio transmissions over the network

Ability to guarantee throughput for high-priority data

(a) III only

(b) I and III only

(c) none

(d) I only



Feedback:

Audio is affected by error rate and latency long before congestion becomes a problem. The throughput boost doesn't change the error rate or the latency and will probably increase the latter. Congestion is not exclusively a problem of link throughput: router or host buffer capacity and CPU power are relevant. Since congestion can still occur, a different mechanism will be needed to guarantee a certain quality of service. See section 2.1.4 of the course notes.

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7.

A TCP implementation that uses a sliding window for flow control has a coding error that causes it to calculate a window size greater than the ideal. What are some of the likely effects of this error?




(a) II only

(b) I only

(c) II and III only

(d) I, II, and III



Feedback:


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8.





(a) II and III only

(b) III only

(c) I and II only

(d) I, II, and III



Feedback:


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9.


(a) Store-and-forward buffer

(b) Retransmit timeout


(d) Maximum Transfer Unit (MTU)



Feedback:


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10.

TCP provides reliability in the presence of packet losses by

(a) congestion control

(b) acknowledgment timeouts

(c) end-to-end flow control

(d) multiple routes for each packet



Feedback:

When an expected acknowledgment has not arrived within a time period, a packet is retransmitted, on the assumption that the data packet was lost. See section 2.1.3 of the course notes.

1.


(a) 1499

(b) 1501

(c) 1502

(d) 1500



Feedback:


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2.





(a) II only

(b) II and III only

(c) III only

(d) I and II only



Feedback:


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3.


(a) Addressing

(b) Error detection using checksum

(c) API provided to application layer




Feedback:


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4.


(a) Maximum Transfer Unit (MTU)

(b) Store-and-forward buffer


(d) Retransmit timeout



Feedback:


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5.


TCP has lower overhead

TCP is a transport-layer protocol

TCP provides reliable transmission

(a) I and II only

(b) II and III only

(c) III only

(d) II only



Feedback:


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6.

Computer A has just received a TCP segment with a header that has the values 1500 and 1501 in the ACK and sequence number fields, respectively, from computer B. The TCP segment has one byte of payload. From this, we know the following about the sequence number sendseqno that computer B will send next:

(a) sendseqno

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