復(fù)習(xí)題chapter3

1、Chapter 3 Transport Layer1. A transport-layer protocol provides for logical communication between. A Application processes B HostsC RoutersD End systems2. Transport-layer protocols run in.A Servers B Clients C Routers D End systems3. In transport layer, the send side breaks application messagesinto,

2、 passesto network layer.A FramesB SegmentsC Data-grams D bit streams4. Services provided by transport layer include.A HTTP and FTP B TCP and IP C TCP and UDP D SMTP5. Which of the following services is not provided by TCP?A Delay guarantees and bandwidth guaranteesB Reliable data transfers and flow

3、controlsC Congestion controls D In-order data transfers6. These two minimal transport-layer services-and-are the only two services that UDP provides!A process-to-process data delivery, error checkingB congestion control, reliable data transferC flow control, congestion controlD In-order data transfe

4、r, error checking7. Port number ' sescop to. A 0, 1023B 0, 65535C 0, 127D 0,2558. The port numbers ranging from to are called well-known port numberand are restricted有一定限制的.A 0, 1023 B 0, 65535C 0, 127D 0,2559. UDP socket identified by two components, they are.A source IP addresses and source po

5、rt numbersB source IP addresses and destination IP addressesC destination IP address and destination port numbersD destination port numbers and source port numbers10. TCP socket identified by a (an).A 1-tupleB 2-tupleC 3-tupleD 4-tuple 元組11. Which of the following applications normally uses UDP serv

6、ices?A SMTPB Streaming multimediaC FTPD HTTP18. Which of the following about TCP connection is not correct?A It is a broadcast connectionB It is a point-to-point connectionC It is a pipelined connectionD It is a full duplex connection19. The SYN segment is used for.A TCP connection setupB TCP flow c

7、ontrolC TCP congestion controlD Closing a TCP connection20. The FIN segment is used for.A TCP connection setup B TCP flow controlC TCP congestion controlD Closing a TCP connection21. How does TCP sender perceive congestion?A Through a timeout eventB Through a receiving duplicate ACK-s eventC Both A

8、and BD Either A or B22. Extending host-to-host delivery to process-to-process delivery is called transport-layer and.A multiplexing and de-multiplexingB storing and forwardingC forwarding and filteringD switching and routing23. UDP is aservice while TCP is a connection-oriented service.A Connectionl

9、essB ReliableC Connection-orientedD In-order24. The UDP header has only four fields, they are.A Source port number, destination port numbe,rlength and checksumB Source port number, destination port number, source IP and destination IP C source IP, destination IP, source MAC address and destination M

10、AC address D source IP, destination IP, sequence number and ACK sequence number 26. The maximum amount of data that can be grabbed and placed in a segment is limited by the.A Maximum segment size (MSS)B MTUC ChecksumD Sequence number27. The MSS is typically set by first determining the length of the

11、 largest link-layer frame that can be sent by the local sending hostthe so-called.A Maximum transmission unit (MTU)B MSSC ChecksumD Sequence number29. BecauseTCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide.A Cumulative acknowledgementsB Selective acknow

12、ledgementsC 3 duplicate ACKsD positive ACKs32. TCP service does not provide.A Reliable data transferB Flow controlC Delay guaranteeD Congestion control33. There are two states in TCP congestion control, which are .A slow start and congestion avoidanceB safe start and congestion avoidanceC slow start

13、 and congestion abandon D safe start and congestion abandon 34. The transport-layer protocol provides logical communication between , andthe network-layer protocol provides logical communication .A hosts, processesB processes, hosts C threads, processes D processes, threads 37. maintains connection-

14、state in the end systems. This connection stateincludes receive and send buffers, congestion-control parameters,and sequenceand acknowledgment number parameters.A UDP B TCP C DNS D HTTP39. With TCP there is no between sending and receiving transport-layerentities.A flow controlB handshakingC. conges

15、tion controlD VC setup40. The Internet _s_ service helps prevent the Internet from entering a state of gridlock.A datagramB congestion controlC sliding windowD timeout event41. Connection setup at the transport layer involves .A serverB only the two end systemsC clientD router42. A layer protocol pr

16、ovides for logical communication between applications.A transportB applicationC networkingD MAC44. The receive side of transportlayer reassembles segmentsinto messages, passes to layer.A ApplicationB NetworkingC PhysicalD MAC46. The port number used by HTTP is .A 80B 25C 110D 5347. The port number u

17、sed by SMTP is .A 80B 25C 110D 5348. The port number used by pop3 is .A 80B 25C 110D 5349. The port number used by DNS is .A 80B 25C 110D 5350. The port number used by FTP is .A 20 and 21B 20C 21D 5351. A UDP socket identified by a tuple(s).A 2B 4C 1D 352. A TCP socket identified by a tuple(s).A 2B

18、4C 1D 353. A TCP socket does not include.A Source MAC addressB Source port numberC Destination IP addressD Destination port number54. Which of following about UDP is not correct.A It is a reliable data transfer protocolB It is connectionlessC no handshaking between UDP sender, receiverD it is a best

19、 effort service protocol55. DNS uses service.A TCPB UDPC Both TCP and UDPD None of above57. Streaming media uses a service normal.lyA TCPB UDPC Both TCP and UDPD None of above58. The UDP header has only fields.A 2B 4C 1D 359. Which of the following does not included in UDP header.A Source port numbe

20、rB Destination port numberC ChecksumD Sequence numberD A computer network may make available multiple transport protocols66. UDP and TCP both have the fields except.A source port numberB destination port numberC checksumD receive window68. Which of the following about TCP is not correct?A It is a co

21、nnectionless protocolB Point-to-point protocolC Reliable, in-order byte steam protocolD Pipelined protocol69. Which of the following about TCP is not correct?A It is a connectionless protocolB full duplex data transfer protocolC connection-oriented protocolD flow controlled protocol70. The maximum a

22、mount of data that can be grabbed and placed in a segment is limited by the.A Maximum segment size (MSS)B MTUC Sequence numberD Check sum71. The MSS is typically set by first determining the length of the largest link-layer frame that can be sent by thelocal sending host (the so-called), and thenwil

23、l fit into a single link-layer frame.A Maximum segment size (MSS)B MTUC Sequence numberD Check sum73. Which of the following field is not used for connection setup and teardown?A Sequence numberB TSTC SYND FIN74.is the byte stream number of first byte in the segment.A Sequence numberB ACK numberC Ch

24、ecksumD port number76. BecauseTCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide acknowledgements.A CumulativeB SelectiveC SingleD Negative77. Fast retransmit means in the case that duplicate ACK-s are received, the TCPsender resend segment before timer ex

25、pires.A 3B 4C 5D 678. TCPmeans sender won t overflow receiver ssbmuiftfteinr gbytotoramnuch,too fast.A Flow controlB Congestion controlC Reliable data transferD Connection-oriented service79. TCP provides flow control by having the sender maintain a variable called theA Receive windowB Congestion wi

26、ndowC Sliding windowD buffer80. How does TCP sender perceive congestion?A TimeoutB 3 duplicate ACK-sC Both A and BD None of above81. Transport protocols run in .A ServersB ClientsC RoutersD End systems82. Which of the following services is not provided by TCP?A Delay guarantees and bandwidth guarant

27、eesB Reliable data transfers and flow controlsC Congestion controlsD In-order data transfers83. Which service does UDP not provide?A multiplexingB de-multiplexingC error-detectionB error-correction85. Which of the following applications normally uses UDP services?A SMTPB Streaming multimediaC FTPD H

28、TTP87. The SYN segment is used for.A TCP connection setupB TCP flow controlC TCP congestion controlD Closing a TCP connection88. Which service helps prevent the internet from entering a state of gridlock?A reliable data transferB flow controlC congestion controlD handshaking procedure90. In the foll

29、owing applications, which one is a bandwidth-sensitive application?A E-mailB web applicationC real-time audioD file transfer91. In the following applications, which one uses UDP?A E-mailB web applicationC file transferD DNS93. is a speeding-matching service-matching the rate which the sender issendi

30、ng against the rate at which the receiving application is reading.A congestion controlB flow controlC sliding-window controlD variable control95. There are 6 flag fields. Which one is to indicate that the receiver should pass the data to the upper layer immediately?A PSHB URGC ACKD RST97. imposes co

31、nstrain on the rate at which a TCP sender can send traffic intothe network.A sliding windowB congestion windowC receive windowD variable window2.Consider the following plot of TCP congestion window size as a function of time.I T 4 -II-1- It LI - L 卻 T-4-1-l +，±- ILL -6 di128Conges%40 2 4 6810 1

32、2 14 16 18 20 22 24 26 28 30 32000Transmission round5 -74 - T_1 .J -ez - 1-1-寸 44 - 丁 T F 4- -I I - -Jz - 一匚Nu - 1r- -r -Fill in the blanks as follow:a) The initial value of Threshold at the first transmission round isb) The value of Threshold at the 1st transmission round is.c) The value of Thresho

33、ld at the 2st transmission round is.d) After the 9th transmission round, segment loss detected by.(A) Timeout(B) Triple duplicate ACKe) After the 19th transmission round, segment loss detected by.(A) Timeout(B) Triple duplicate ACKf) During transmission round, the 1秒 segment is sent.3.Consider the T

34、CP reliable data transfer in the given graph. If in Segment 1 s Sequence number =10,data="ACase f川 in the following blanks.a) In Segment 2, ACK number=;b) In Segment 3, Sequence number =; data= "0123456789”c) If there are some bits corrupted in segment 3 when it arrives Host B, then the ACK number in Segment 5 is ; and the ACK number in Segment 6 is .14. The client A wants to request a Web pagfrom Server B. Suppose the URL of the page is 00/experiment, and also it wants to receive French version of object. The time-sequence diagram