复习题chapter3

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 _, 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 data 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 controlD In-order data transfer, error checking7. Port numbers scope is _ to _. A 0, 1023B 0, 65535 C 0, 127D 0,2558. The port numbers ranging from _to _ are called well-known port number and are restricted 有一定限制的.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 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元组11. Which of the following applications normally uses UDP services? 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 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 ACK-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-oriented 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 MAC address and destination MAC addressD source IP, destination IP, sequence number and ACK sequence number26. 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 largest link-layer frame that can be sent by the local sending host-the so-called_.A Maximum transmission unit (MTU)B MSSC ChecksumD Sequence number29. Because TCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide_. A Cumulative acknowledgementsB Selective acknowledgementsC 3 duplicate ACKsD positive ACKs32. 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 avoidanceB 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, processes D processes, threads37. _ maintains connection-state in the end systems. This connection state includes receive and send buffers, congestion-control parameters, and sequence and acknowledgment number parameters. A UDPB TCPC DNSD HTTP39. With TCP there is no _ 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 datagramB congestion controlC sliding window D timeout event41. Connection setup at the 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 MAC44. The receive side of transport layer reassembles segments into messages, passes to _layer. A ApplicationB NetworkingC PhysicalD MAC46. 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 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 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 effort service protocol55. DNS uses _ service. A TCPB UDPC Both TCP and UDPD None of above57. 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 does not included in UDP header. A Source port numberB 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 number B destination port numberC checksum D receive window68. 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 connection-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 that can be sent by the local sending host (the so-called_), and then will 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 FIN 74. _ is the byte stream number of first byte in the segment. A Sequence numberB ACK numberC Checksum D port number76. Because TCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide _ acknowledgements. A Cumulative B SelectiveC SingleD Negative77. Fast retransmit means in the case that _ duplicate ACK-s are received, the TCP sender resend segment before timer expires.A 3B 4C 5D 678. TCP_ means sender wont overflow receivers buffer by transmitting too much, 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 the _. A 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 Servers B Clients C Routers D End systems82. Which of the following services is not 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 multiplexing B de-multiplexingC error-detection B error-correction85. Which of the following applications normally uses UDP services? A SMTP B Streaming multimedia C FTP D HTTP87. 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 transfer B flow controlC congestion control D handshaking procedure90. In the following applications, which one is a bandwidth-sensitive application? A E-mail B web application C real-time audio D file transfer91. In the following applications, which one uses UDP? A E-mail B web application C file transfer D DNS93. _ is a speeding-matching service-matching the rate which the sender is sending against the rate at which the receiving application is reading.A congestion control B flow controlC sliding-window control D 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 PSH B URG C ACK D RST97. _ imposes constrain on the rate at which a TCP sender can send traffic into the network. A sliding window B congestion window C receive window D variable window2.Consider the following plot of TCP congestion window size as a function of time.14180263000264810121620222402832Congestion window sizeTransmission round481216Fill in the blanks as follow:a) The initial value of Threshold at the first transmission round is _.b) The value of Threshold at the 11st transmission round is _.c) The value of Threshold at the 21st 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 18th segment is sent. 3.Consider the TCP reliable data transfer in the given graph. If in Segment 1s Sequence number =10,data=“AC”, please fill 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 _. 1 3 4 6 2 5 74. The client A wants to request a Web page from Server B. Suppose the URL of the page is 172.16.0.200/experiment, and also it wants to receive French version of object. The time-sequence diagram is shown below, please fill in the blanks. 12345Packet to Packet are TCP connections segment, then:Packet : SYN flag bit= a ACK flag bit= b Sequence number= 92Packet : SYN flag bit=1 ACK flag bit= c Sequence number=100Packet : SYN flag bit= d ACK flag bit=1 Sequence number= e 5. Consider sending an object of size O=100 Kbytes from server to client. Let S=536 bytes and RTT=100msec. Suppose the transport protocol uses static windows with window size W. (1) For a transmission rate of 25 kbps, determine the minimum possible latency. Determine the minimum window size that achieves this latency. (2) Repeat (1) for 100 kbps.6. Consider the following plot of TCP congestion window size as a function of time. Please fill in the blanks as below. 14182630026481012162022242832Congestion window sizeTransmission round481216a) The initial value of Threshold at the first transmission round is_.b) The value of Threshold at the 11th transmission round is_. c) The value of Threshold at the 21st transmission round is_. d) After the 9th transmission round, _ occurs. e) After the 19th transmission round, _ are detected.