计算机网络英文题库(附答案)chapter3解析

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

3、controlsC 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 trans

4、fer, error 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 por

5、t 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 applications normally uses UDP servic

6、es?A SMTPB Streaming 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 followi

7、ng about reliable 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

8、?A TCP B rdt3.0C 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 individ

9、ually acknowledges 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 poi

10、nt-to-point connectionC 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

11、con gestio n con trolD 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-layer _and _.A multip

12、lex ing and de-multiplex ingB stori ng and forward ingC forwardi ng and filteri ngD switchi ng and routi ng23. UDP is a_service 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 p

13、ort nu mber, desti nati on 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

14、 are two 16-bit in tegers: 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 Sequ

15、e nee nu mber27. The MSS is 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

16、to transmitthis file with TCP, 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

17、 Selective ack no wledgeme ntsC 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 is_s.A 0.45B 0.6C 0.7D 0.831. ProvidedRcvBuffer=20,LastByteRcvd=20,LastByteRead=15,thenRcvWin dow=_ .A 14B 15C 16D 1032. T

18、CP service does not provide _.A Reliable 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 sa

19、fe start and con gesti on aba ndon34. 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 I

20、nternet employs the _ protocol.A FTP B 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 buffer

21、s, 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 no _ between sending and receiving transport-layerentities.A

22、 flow controlB handshakingC. congestion 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 server B only the two end systemsC

23、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 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. Th

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