計算機(jī)網(wǎng)絡(luò)英文題庫附答案chapter3推薦文檔

1、Chapter 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 application messages into ,

2、passes tonetwork layer.A FramesB SegmentsC Data-gramsD 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 data transfers and flow cont

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

4、or checking7. Port number sesicso_p_ to .A 0, 1023B 0, 65535C 0, 127D 0,2558. The port numbers ranging from to are called well-known port numberand are restricted.A 0, 1023B 0, 65535C 0, 127D 0,2559. UDP socket identified by two components, they are .A source IP addresses and source port numbersB so

5、urce 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 applications normally uses UDP services?A SMTPB Str

6、eaming multimediaC FTPD HTTP12. Reliable data transfer protocol over a perfectly reliable channel is.A rdt1.0 B rdt2.0 C rdt3.0 D rdt2.113. Reliable data transfer protocol over a channel with bit errors and packet losses is _A rdt1.0 B rdt2.0 C rdt3.0 D rdt2.114. Which of the following about reliabl

7、e data transfer over a channel with bit errors i s not correct?A RDT2.0: assuming ACK and NAK will not be corruptedB RDT2.1: assuming ACK and NAK can be corruptedC RDT2.2: only use ACK-sD RDT2.2: use both ACK-s and NAK-s15. Which of the following protocols is not pipelining protocols?A TCP B rdt3.0C

8、 GO-BACK-N D selective repeat16. Which of the following is not correct about GBN protocol?A Only using ACK-sB Using cumulative ACK-sC Receiver discards all out-of-order packetsD It is not pipelined protocol17. Which of the following is not correct about SR protocol?A receiver individually acknowledg

9、es all correctly received packetsB sender only resends packets for which ACK not receivedC It limits sequence number of sent but un-ACK-ed packetsD It is not a pipelined protocol18. Which of the following about TCP connection is not correct?A It is a broadcast connectionB It is a point-to-point conn

10、ectionC It is a pipelined connectionD It is a full duplex connection19. The SYN segme nt is used for.A TCP conn ecti on setupB TCP flow controlC TCP con gestio n con trolD Clos ing a TCP conn ecti on20. The FIN segme nt is used for.A TCP conn ecti on setupB TCP flow controlC TCP con gestio n con tro

11、lD Clos ing a TCP conn ecti on21. How does TCP sender perceive congestion?A Through a timeout eve ntB Through a recei ving duplicate ACK-s eve ntC Both A and BD Either A or B22. Extending host-to-host delivery to process-to-process delivery is calledtransport-layerand.A multiplex ing and de-multiple

12、x ingB stori ng and forward ingC forwardi ng and filteri ngD switchi ng and routi ng23. UDP is aservice while TCP is a conn ecti on-orie nted service.A Conn ecti onl essB ReliableC Conn ectio n-orie ntedD ln-o rder24. The UDP header has on ly four fields, they are.A Source port nu mber, desti nati o

13、n port nu mber, le ngth and checksumB Source port number, destination port number, source IP and destination IPC source IP, desti nati on IP, source MAC address and dest in ati on MAC addressD source IP, dest in ati on IP, seque nee nu mber and ACK seque nee nu mber25. There are two 16-bit in tegers

14、: 1110 0110 0110 0110, 1101 0101 0101 0101. Their checksum is .A 0100010001000011B 10111011101111001111111111111111100000000000000026. The maximum amount of data that can be grabbed and placed in a segment is limited by the.A Maximum segme nt size (MSS)B MTUC ChecksumD Seque nee nu mber27. The MSS i

15、s typically set by first determining the length of the largest link-layerframe that can be sent by the local sending host-the so-called.A Maximum tran smissi on unit (MTU)B MSSC ChecksumD Seque nee nu mber28. A File size of 500,000bytes, MSS equals lOOObytes. When we want to transmitthis file with T

16、CP, the sequence number of the first segment is 0, and the sequence nu mber of the sec ond segme nt i.A 1000B 999C 1001D 50000029. Because TCP on ly ack no wledges bytes up to the first missi ng byte in the stream,TCP is said to provide.A Cumulative ack no wledgeme ntsB Selective ack no wledgeme nts

17、C 3 duplicate ACKsD positive ACKs30. Provided a =0.t25re nt value of Estimated-RTT is 0.4s, Sample-RTT is 0.8s,the n the new value of Estimated-RTT iss.A 0.45B 0.6C 0.7D 0.831. ProvidedRcvBuffer=20,LastByteRcvd=20,LastByteRead=15,thenRcvWi ndow=_ .A 14B 15C 16D 1032. TCP service does not provide.A R

18、eliable data tran sferB Flow con trolC Delay guara nteeD Con gesti on con trol33. There are two states in TCP con gesti on con trol, which are.A slow start and con gesti on avoida nceB safe start and con gestio n avoida nceC slow start and con gesti on aba ndonD safe start and con gesti on aba ndon3

19、4. The tran sport-layer protocol provides logical com muni cati on betwee n, andthe n etwork-layer protocol provides logical com muni cati on.A hosts, processesB processes, hostsC threads, processesD processes, threads35. To implement the multicast services the Internet employs the protocol.A FTP B

20、TCP C IGMP D UDP36. If an application developer chooses protocol, then the application process isalmost directly talking with IP.A HTTPB RIPC CSMA/CDD UDP37. maintains connection-state in the end systems. This connection stateincludes receive and send buffers, congestion-control parameters,and seque

21、nce 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 no between sending and receiving transport-layerentities.A flow controlB handshakingC. congestion contr

22、olD 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 server B only the two end systemsC client D router42. A layer protocol provides f

23、or logical communication between applications.A transportB applicationC networkingD MAC43. In static congestion window, if it satisfies W*S/R RTT + S/R, the Latency isA W*S/R RTT+ 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 s

24、egments 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 smoothed out in the computation of the EstimatedRTTB The timeout should be less than the connection s RTTC Suppose that the las

25、t SampleRTT in a TCP connection is equal to 1 sec. Then thecurre nt value of Timeoutl nterval will n ecessarily be 1 secD Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Then the curre nt value of Timeoutl nterval will n ecessarily be 1 sec46. The port number used by HTTP is .

26、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 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

27、 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 number54. Which of following about UDP is not correct.A It is a reliable data transfer protocolB It is connectionlessC no handshaking betw

28、een 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 correct?A Finer application-level control over what data is sent, and whenB No connection establishment (which can add delay), so no delay

29、 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 uses 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 do

30、es 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

31、 maximum amount of application-layer data in the segment B The MSS is the maximum size of the TCP segment including headers C The MSS is typically set by MTUD The MTU means the largest link-layer frame62. The job of gathering data chunks, encapsulating each data chunk with header information to crea

32、te segments and passing the segments to the network is calledA multiplexingB de-multiplexingC forwardingD routing63. In the following four descriptions about the relationship between the transport layer and the network layer, which one is not correct?A The transport-layer protocol provides logical c

33、ommunication between hostsB The transport-layer protocol provides logical communication between processesC The services that a transport-layer protocol can provide are often constrained by the service model of the network-layer protocolD A computer network may make available multiple transport proto

34、cols64. Suppose the following three 8-bit bytes: 01010101, 01110000, 01001100. What sthe 1s complement of the sum of these 8-bit bytes?A 00010001B 11101101C 00010010D 1000100065. The following four descriptions about multiplexing and de-multiplexing, which one is correct?A A UDP socket is identified

35、 by a two-tuples consisting of a source port number and a destination port number.B If two UDP segment have different source port number, they may be directed to the same destination process.C If two TCP segments with different source port number, they may be directed to the same destination process

36、.D If two TCP segments with same destination IP address and destination port number, they must be the same TCP connection.66. UDP and TCP both have the fields except .A source port numberB destination port numberC checksumD receive window67. If we define N to be the window size, base to be the seque

37、ncenumber of the oldest unacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval nextseqnum,base+N-1 corresponds to packet that .A can be sent immediatelyB have already been transmitted and acknowledgedC cannot be usedD have been sent but not yet acknowled

38、ged68. Which of the following about TCP is not correct? A It is a connectionless 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 con

39、nection-oriented protocolD flow controlled protocol70. 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 Sequence numberD Check sum71. The MSS is typically set by first determining the length of the largest link-layer frame t

40、hat can be sent by the local sending host (the so-called), and then will fitinto a single link-layer frame.A Maximum segment size (MSS)B MTUC Sequence numberD Check sum72. The MSS is the maximum amount of layer data in the segment, not themaximum size of the TCP segment including headers.A Applicati

41、onB TransportC NetworkingD Link73. 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 ChecksumD port number75. is the byte sequence numbers of next byte e

42、xpected from other side.A Sequence numberB ACK numberC ChecksumD port number76. Because TCP 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

43、are received, the TCPsender resend segment before timer expires.A 3B 4C 5D 678. TCP means sender won t overflow receiver ssbmuiftfteinrgbytotoramnuch,too fast.A Flow controlB Congestion controlC Reliable data transferD Connection-oriented service79. TCP provides flow control by having the sender mai

44、ntain a variable called theA Receive windowB Congestion windowC 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 no

45、t provided by TCP?A Delay guarantees and bandwidth guaranteesB Reliable data transfers and flow controlsC Congestion controlsD In-order data transfers83. Which service does UDP not provide?A multiplexingB de-multiplexingC error-detectionD error-correction84. There are three major events related to d

46、ata transmission and retransmission in the TCP sender, which one is not in it?A data received from application aboveB de-multiplexing segmentC timer timeoutD ACK receipt85. Which of the following applications normally uses UDP services?A SMTPB Streaming multimediaC FTPD HTTP86. Which of the followin

47、g 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 connection87. The SYN segment is used for.A TCP connection setupB TCP flow controlC TCP congestion controlD Closing a TCP connection88. Which ser

48、vice helps prevent the internet from entering a state of gridlock?A reliable data transferB flow controlC congestion controlD handshaking procedure89. The Internet s is responsible for moving packets from one host to another.A application layerB transport layerC network layerD link layer90.In the fo

49、llowing 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 DNS92. In the following four descriptions, which one is correct?A If one host

50、tsransport layer uses TCP, then its network layer must use virtual-circuit network.B Datagram network provides connection serviceC The transport-layer connection service is implemented in the routerD The network-layer connection service is implemented in the router as well as in the end system.93. i

51、s a speeding-matching service-matching the rate which the sender issending against the rate at which the receiving application is reading.A congestion controlB flow controlC sliding-window controlD variable control94. In the following four descriptions about Rcv-Window, which one is correct?A The si

52、ze of the TCP RcvWindow never changesthroughout the duration of the connectionB The size of the TCP RcvWindow will change with the size of the TCP RcvBufferC The size of the TCP RcvWindow must be less than or equal to the size of the TCP RcvBufferD Suppose host A sends a file to host B over a TCP co

53、nnection, the number of unacknowledged bytes that A sends cannot exceed the size of the size of the RcvWindow.95. 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 RST96. Suppose the TCP receiver receives the segm

54、ent that partially or completely fills in gap in received data, it will .A immediately send ACKB immediately send duplicate ACKC wait some time for arrival of another in-order segmentD send single cumulative97. imposes constrain on the rate at which a TCP sender can send traffic intothe network.A sl

55、iding windowB congestion windowC receive windowD variable window98. Flow control and congestion control are same at that they all limit the rate of the sender, but differ in that .A flow control limits its rate by the size of RcvWindow, but congestion control by the traffic on the linkB congestion c

56、ontrol limits its rate by the size of RcvWindow, but flow control by the traffic on the linkC flow control mainly is accomplished by the sender, but congestion control by the receiver.D flow control mainly is accomplished by the receiver, but congestion control bythe link.99. This job of delivering the data in a transport-layer segment to the correct socket is called .A multiplexingB de-multiplexingC forwardingD routing100. If we define N t