计算机网络英文题库(附答案)chapter3

B Through a receiving duplicate ACK-s event C Both A and B D Either A or B

22. Extending host-to-host delivery to process-to-process delivery is called transport-layer ____ and . A multiplexing and de-multiplexing B storing and forwarding C forwarding and filtering D switching and routing

23. UDP is a ____ service while TCP is a connection-oriented service. A Connectionless B Reliable

C Connection-oriented D In-order

24. The UDP header has only four fields, they are____.

A Source port number, destination port number, length and checksum B Source port number, destination port number, source IP and destination IP

C source IP, destination 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 011 B 100 C 111 D 000

26.The maximum amount of data that can be grabbed and placed in a segment is limited by the____. A Maximum segment size (MSS) B MTU C Checksum D 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-called____.

A Maximum transmission unit (MTU) B MSS C Checksum D 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 0, and the sequence number of the second segment is ____. A 1000 B 999 C 1001 D 500000

29. Because TCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide____. A Cumulative acknowledgements B Selective acknowledgements C 3 duplicate ACKs D positive ACKs

30. Provided α=, current value of Estimated-RTT is , Sample-RTT is , then

the new value of Estimated-RTT is ____s. A B C D

31.Provided

RcvBuffer=20,LastByteRcvd=20,LastByteRead=15,

then

RcvWindow=____. A 14 B 15 C 16 D 10

32. TCP service does not provide____.

A Reliable data transfer B Flow control C Delay guarantee D Congestion control 33. There are two states in TCP congestion control, which are ____. A slow start and congestion avoidance B safe start and congestion avoidance C slow start and congestion abandon D safe start and congestion abandon

34. The transport-layer protocol provides logical communication between ____, and the network-layer protocol provides logical communication ____. A hosts, processes B processes, hosts

C threads, processes D processes, threads

35. To implement the multicast services the Internet employs the ____ protocol.

A FTP B TCP C IGMP D UDP

36. If an application developer chooses ____ protocol, then the application process is almost directly talking with IP. A HTTP B RIP C CSMA/CD D UDP

37. ____ 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 UDP

B TCP

C DNS

D HTTP

38. The host that initiates the session in the Internet is labeled as ____. A server B user agent C client

D router

39. With TCP there is no _____ between sending and receiving transport-layer entities. A flow control

B handshaking

D VC setup

C. congestion control

40. The Internet’s ____ service helps prevent the Internet from entering a state of gridlock. A datagram

B congestion control

C sliding window D timeout event

41. Connection setup at the transport layer involves ____. A server C client

B only the two end systems

D router

42. A ____layer protocol provides for logical communication between applications. A transport