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1、. Chapter 3 Transport Layer 1. A transport-layer protocol provides for logical communication between . AApplication processes BHosts Routers End systems 2. Transport-layer protocols run in . AServers Clients Routers End systems 3. In transport layer, the send side breaks application messages into ,
2、passes to network layer. Frames Segments Data-grams Dbit streams 4. Services provided by transport layer include . AHTTP and FTP BTCP and IP CTCP and UDP DSMTP 5. Which of the following services is not provided by TCP? ADelay guarantees and bandwidth guarantees BReliable data transfers and flow cont
3、rols CCongestion controls DIn-order data transfers 6. These two minimal transport-layer services- and -are the only two services that UDP provides! Aprocess-to-process data delivery, error checking Bcongestion control, reliable data transfer flow control, congestion control In-order data transfer, e
4、rror checking Port numbers scope is to . A0, 1023 B0, 65535 C0, 127 D0,255 The port numbers ranging from to are called well-known port number and are restricted. A0, 1023 B0, 65535,.,1,.,.,2,.,.,C0, 127 D0,255 9. UDP socket identified by two components, they are . Asource IP addresses and source por
5、t numbers source IP addresses and destination IP addresses destination IP address and destination port numbers Ddestination port numbers and source port numbers 10. TCP socket identified by a (an) . A1-tuple 2-tuple 3-tuple 4-tuple 11. Which of the following applications normally uses UDP services?,
6、SMTP Streaming multimedia CFTP DHTTP 12.,Reliabledatatransfer,protocoloveraperfectlyreliable,A,channelis . rdt1.0B,rdt2.0 transfer,Crdt3.0 protocolover,Drdt2.1 achannelwithbit,13.Reliabledata errorsand,packetlosses,rdt1.0,is . Crdt3.0D,rdt2.1 aboutreliabledatatransferover,isnotcorrect? NAKwillnotbec
7、orrupted,NAKcanbecorrupted,withbit assuming assuming onlyuse useboth,errors ACKand ACKand ACK-s ACK-s,andNAK-s protocolsisnotpipeliningproto,TCP,ofthefollowing Brdt3.0,aboutGBNprotoco,Only Using,usingACK-s cumulativeACK-s,Receiverdiscardsallout-of-orderpackets Itisnotpipelinedprotocol,ABrdt2.0 14.Wh
8、ichofthefollowing achannel RDT2.0: RDT2.1: RDT2.2: RDT2.2: 15.Which cols? A CGO-BACK-NDselectiverepeat Whichofthefollowingisnotcorrect l? A B C D WhichofthefollowingisnotcorrectaboutSRprotocol ? Areceiverindividuallyacknowledgesallcorrectlyreceived,packets BsenderonlyresendspacketsforwhichACKnotrece
9、ived,.,. numberofsentbutun-ACK-edpackets,Itlimitssequence Itisnotapipelinedprotocol,18. Which of the following about TCP connection is not correct? AIt is a broadcast connection BIt is a point-to-point connection CIt is a pipelined connection DIt is a full duplex connection 19. The SYN segment is us
10、ed for . ATCP connection setup TCP flow control TCP congestion control Closing a TCP connection 20. The FIN segment is used for . ATCP connection setup TCP flow control TCP congestion control Closing a TCP connection 21.How does TCP sender perceive congestion? AThrough a timeout event BThrough a rec
11、eiving duplicate ACK-s event CBoth A and B DEither A or B 22. Extending host-to-host delivery to process-to-process delivery is called transport-layer and . Amultiplexing and de-multiplexing Bstoring and forwarding Cforwarding and filtering Dswitching and routing 23. UDP is aservice while TCP is a c
12、onnection-oriented service. AConnectionless Reliable Connection-oriented DIn-order 24. The UDP header has only four fields, they are .,.,3,Source port number, destination port number, length and checksum Source port number, destination port number, source IP and destination IP C,source IP, destinati
13、on IP, source MAC address and destination MAC,address D source IP, destination IP, sequence number and ACK sequence number 25. There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Their checksum is . A 0100010001000011 B 1011101110111100,.,.,.,C1111111111111111 D1000000000000000
14、26.The maximum amount of data that can be grabbed and placed in a segment is limited by the . AMaximum segment size (MSS) BMTU Checksum Sequence number 27. 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-calle
15、d . A Maximum transmission unit (MTU) B MSS Checksum Sequence number 28. 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 .,29. Because TCP only acknowledges bytes up to the first missing byte in the stream, T
16、CP is said to provide . ACumulative acknowledgements BSelective acknowledgements C3 duplicate ACKs Dpositive ACKs 30. Provided =0.125, current value of Estimated-RTT is 0.4s, Sample-RTT is 0.8s, then the new value of Estimated-RTT iss. A0.45 B0.6 C0.7 D0.8,then,31.Provided RcvWindow=,RcvBuffer=20,LastByteRcvd=20,LastByteRead=15, .,14 15 16 10 32. TCP service does not provide .,.,4,AReliable data transfer CDelay guarantee,BFlow control DCong
