课程名称︰计算机网路 课程性质︰资工系必修 课程教师︰周承复 开课学院：电资学院 开课系所︰资工系 考试日期（年月日）︰ 考试时限（分钟）：180分钟 试题 : Question 1: "Quickies" (35%) Answer each of the following questions briefly, i.e., in at most a few sentences. a) (15%) What is the major differences between TCP and UDP? Why DNS uses UDP instead of TCp for its service? b) (10%) According to the course's textbook, how many layers are included in the Internet (give their names too)? Give one example of application, or protocol, or device, that corresponding to each layer. c) (10%) What is the difference between a recursive query and an iterated query in the DNS? Question 2: True or False (12%) if your answer is False, please explain your reason a. (3%) In a circuit switched network, all data belonging to a connection traverses the same route, whereas in a packet switched network, different packets belonging to the same connection may take different routes. b. (3%) With non-persistent connections between browser and origin server, it is possible for a single TCP segment to carry two distinct HTTP request messages. c. (3%) HTTP response messages can have an empty message body. d. (3%) The Date: header in the HTTP response message indicates when the obiect in the response was last modified. Question 3: P2P System (30%) In BitTorrent, the file is divided into 256Kb chunks. a. (10%) Please explain the reason why BitTorrent chooses the chunk size is 256Kb. That is, you could explain what the pros and cons for the large chunk size (and the small chunk size) are. b. (10%) What is the free rider problem in BitTorrent? Please explain how BitTorrent address the free rider problem. c. (10%) NTU Computer Center hires you as the p2p expert to reduce its rising bandwidth costs due the rising use of BitTorrent. How would you address this problem? Question 4: Video Streaming and CDN a. (10%) What is the major challenge for video streaming over Internet b. (10%) Please explain what spatial coding and temporal coding are for the video. c. (10%) Please list four techniques to address the issue of the video streaming over Internet. Question 5: Socket Programming (10%) This is a socket programming with TCP protocol in C language. Please fill in the https://i.imgur.com/CtKWQCp.jpg ----- Sent from JPTT on my iPhone --

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