计算机网络英文题库（附答案）chapter3（推荐文档）

the link.

99. This job of delivering the data in a transport-layer segment to the correct socket is called ____.

A multiplexing B de-multiplexing C forwarding D routing

100. If we define N to be the window size, base to be the sequence number of the oldest unacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [base, nextseqnum-1] corresponds to packet that ____. A can be sent immediately

B have already been transmitted and acknowledged C cannot be used

D have been sent but not yet acknowledged

101. ____ are the two types of transport services that the Internet provides to the applications.

A TCP and UDP

B connection-oriented and connectionless service C TCP and IP

D reliable data transfer and flow control

102. In the following descriptions about persistent connection, which one is not correct?

A The server leaves the TCP connection open after sending a response B Each TCP connection is closed after the server sending one object

C There are two versions of persistent connection: without pipelining and with pipelining

D The default mode of HTTP uses persistent connection with pipelining 103. The field of Length in UDP segment specifies the length of ____. A the UDP segment, not including the header B the UDP segment, including the header C the UDP segment’s header D the Length field

104. In TCP segment header, which field can implement the reliable data transfer? A source port number and destination port number B sequence number and ACK number

C urgent data pointer D Receive window

105. In the following four descriptions about TCP connection management, which one is not correct?

A Either of the two processes participating in a TCP connection can end the connection

B If the FIN bit is set to 1, it means that it wants to close the connection

C In the first two step of the three-way handshake, the client and server randomly choose an initial sequence number

D In the three segments of the three-way handshake, the SYN bit must be set to 1 106. Suppose host A sends two TCP segments back to back to host B over a TCP connection. The first segment has sequence number 42, and the second has sequence number 110. If the 1st is lost and 2nd arrives at host B. What will be the acknowledgment number?

A 43 B ACK42 C 109 D ACK110

1. Consider sending an object of size O=500,000bytes from server to client. Let S=500 bytes and RTT=0.2s. Suppose the transport protocol uses static windows with window size 5. For a transmission rate of 100Kbps, determine the latency for sending the whole object. Recall the number of windows K=O/ WS), and there is K-1 stalled state (that is idle time gaps).

2.Consider the following plot of TCP congestion window size as a function of time.

16 Fill 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 ACK

e) After the 19th transmission round, segment loss detected by ____.

(A) Timeout

(B) Triple duplicate ACK

f) During ____ transmission round, the 18th segment is sent.

3.Consider the TCP reliable data transfer in the given graph. If in Segment 1’s 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 ____. Congestion window size 12 8 4 0 2 4 6 8 10 12 14 16 1820 22 2426 28 3032 0 0 0

Transmission round

1 2 3 4 5 6 7

4. 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.

1 2 3 4 5

Packet① to Packet③ are TCP connection’s segment, then: Packet ①: SYN flag bit= a ACK flag bit= b Sequence number= 92 Packet ②: SYN flag bit=1