计算机网络英文题库附答案chapter3.docx

1、计算机网络英文题库附答案chapter3Chapter 3 Transport Layer1. A transport-layer protocol provides for logical communication between _.A Application processesB HostsC RoutersD End systems2. Transport-layer protocols run in _.A ServersB ClientsC RoutersD End systems3. In transport layer, the send side breaks applic

2、ation messages into _, passes to network layer.A FramesB SegmentsC Data-grams D bit streams4. Services provided by transport layer include _.A HTTP and FTPB TCP and IPC TCP and UDPD SMTP5. Which of the following services is not provided by TCP? A Delay guarantees and bandwidth guaranteesB Reliable d

3、ata transfers and flow controlsC Congestion controlsD 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 con

4、trolD In-order data transfer, error checking7. Port numbers scope is _ to _. A 0, 1023B 0, 65535C 0, 127D 0,2558. The port numbers ranging from _to _ are called well-known port number and are restricted.A 0, 1023B 0, 65535C 0, 127D 0,2559. UDP socket identified by two components, they are _.A source

5、 IP addresses and source port 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-tuple11. Which of the following applicat

6、ions normally uses UDP services? A SMTPB Streaming multimediaC FTPD HTTP12.Reliabledatatransferprotocoloveraperfectlyreliablechannelis_.Ardt1.0Brdt2.0Crdt3.0Drdt2.113.Reliabledatatransferprotocoloverachannelwithbiterrorsandpacketlossesis_.Ardt1.0Brdt2.0Crdt3.0Drdt2.114.Whichofthefollowingaboutreliab

7、ledatatransferoverachannelwithbiterrorsisnotcorrect?ARDT2.0:assumingACKandNAKwillnotbecorruptedBRDT2.1:assumingACKandNAKcanbecorruptedCRDT2.2:onlyuseACK-sDRDT2.2:usebothACK-sandNAK-s15.Whichofthefollowingprotocolsisnotpipeliningprotocols?ATCP Brdt3.0CGO-BACK-N Dselectiverepeat16.Whichofthefollowingi

8、snotcorrectaboutGBNprotocol?AOnlyusingACK-sBUsingcumulativeACK-sCReceiverdiscardsallout-of-orderpacketsDItisnotpipelinedprotocol17.WhichofthefollowingisnotcorrectaboutSRprotocol?AreceiverindividuallyacknowledgesallcorrectlyreceivedpacketsBsenderonlyresendspacketsforwhichACKnotreceivedCItlimitssequen

9、cenumberofsentbutun-ACK-edpacketsDItisnotapipelinedprotocol18. 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

10、 setupB TCP flow controlC TCP congestion controlD Closing a TCP connection20. The FIN segment is used for_.A TCP connection setupB 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 A

11、CK-s eventC Both A 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 a _ service while TCP is a connection-orie

12、nted service. A ConnectionlessB ReliableC Connection-orientedD In-order24. The UDP header has only four fields, they are_. A Source port number, destination port number, length and checksumB Source port number, destination port number, source IP and destination IPC source IP, destination IP, source

13、MAC address and destination MAC addressD source IP, destination IP, sequence number and ACK sequence number25. There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Their checksum is_. A 010*B 1011101110111100C 111111*1D 100000000000000026. The maximum amount of data that can be g

14、rabbed 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 largest link-layer frame that can be sent by the local sending host-the so-called_.A Maximum transmission unit (MTU)B MSSC

15、 ChecksumD Sequence number28. A File size of 500,000bytes, MSS equals 1000bytes. When we want to transmit this file with TCP, the sequence number of the first segment is 0, and the sequence number of the second segment is _. A 1000B 999C 1001D 50000029. Because TCP only acknowledges bytes up to the

16、first missing byte in the stream, TCP is said to provide_. A Cumulative acknowledgementsB Selective acknowledgementsC 3 duplicate ACKsD positive ACKs30. Provided =0.125, current value of Estimated-RTT is 0.4s, Sample-RTT is 0.8s, then the new value of Estimated-RTT is _s. A 0.45B 0.6C 0.7D 0.831. Pr

17、ovided RcvBuffer=20,LastByteRcvd=20,LastByteRead=15, then RcvWindow=_. A 14B 15C 16D 1032. TCP service does not provide_. A Reliable data transfer B Flow controlC Delay guarantee D Congestion control33. There are two states in TCP congestion control, which are _. A slow start and congestion avoidanc

18、eB safe start and congestion avoidanceC slow start and congestion abandonD safe start and congestion abandon34. The transport-layer protocol provides logical communication between _, and the network-layer protocol provides logical communication _. A hosts, processes B processes, hostsC threads, proc

19、esses D processes, threads35.ToimplementthemulticastservicestheInternetemploysthe_protocol.AFTPBTCPCIGMPDUDP36. If an application developer chooses _ protocol, then the application process is almost directly talking with IP. A HTTPB RIPC CSMA/CDD UDP37. _ maintains connection-state in the end system

20、s. This connection state includes receive and send buffers, congestion-control parameters, and sequence and acknowledgment number parameters. A UDP B TCP C DNS D HTTP38. The host that initiates the session in the Internet is labeled as _.A server B user agent C client D router39. With TCP there is n

21、o _ between sending and receiving transport-layer entities. A flow control B handshakingC. congestion control D VC setup40. The Internets _ service helps prevent the Internet from entering a state of gridlock. A datagram B congestion controlC sliding window D timeout event41. Connection setup at the

22、 transport layer involves _. A server B only the two end systemsC client D router42. A _layer protocol provides for logical communication between applications. A transportB applicationC networkingD MAC43. In static congestion window, if it satisfies W*S/R RTT + S/R, the Latency is _. A W*S/R ( RTT+

23、S/R) B 2RTT + O/RC 2RTT + O/R + (k-1)W* S/R- (RTT + S/R) D 2RTT + S/R44. The receive side of transport layer reassembles segments into messages, passes to _layer. A ApplicationB NetworkingC PhysicalD MAC45. In the following four options, which one is correct? A The variations in the SampleRTT are sm

24、oothed out in the computation of the EstimatedRTTB The timeout should be less than the connections RTTC Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Then the current value of TimeoutInterval will necessarily be1 secD Suppose that the last SampleRTT in a TCP connection is eq

25、ual to 1 sec. Then the current value of TimeoutInterval will necessarily be1 sec46. The port number used by HTTP is _. A 80B 25C 110D 5347. The port number used 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

26、 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 4C 1D 353. A TCP socket does not include_. A Source MAC addressB Source port numberC Destination IP addressD Destination port num

27、ber54. 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 effort service protocol55. DNS uses _ service. A TCPB UDPC Both TCP and UDPD None of above56. Which of following about UDP is

28、 correct?A Finer application-level control over what data is sent, and when B No connection establishment (which can add delay), so no delay for establish a connectionC No connection state (so, UDP can typically support many active clients)D Large packet header overhead (16-B)57. Streaming media use

29、s a _ service normally. A 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 numberB Destination port numberC ChecksumD Sequence number60. Which of the following is not a pipelining protocol. A Rdt1.0B Go-Back-NC Selective repeatD TCP61. In the following four descriptions about MSS and MTU, which one is not correct? A The MSS is the maximum amount of application-layer data in the se