Computer Science Assignment – expert computer networks

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1102/159.334 CP ALB Internal -Page 1 of 7 -MASSEY UNIVERSITY ALBANY CAMPUS EXAMINATION FOR 159.334 Computer Networks Semester Two -2011 Time allowed: THREE (3) hours Attempt ALL 6 (six) questions. All questions are of equal value. This examination contributes 60% to the final assessment. Calculators permitted – no restrictions. 1102/159.334 CP ALB Internal -Page 2 of 7 -Question 1: a) Name four socket functions (C functions) used to create client/server applications. [4 marks] b) Name the five layers in a typical TCP/IP computer network. [2 marks] c) What are the services provided by TCP? [2 marks] d) The source and destination port numbers are included in the packet header. Which layer needs to be able to read these port numbers? [2 marks] 1102/159.334 CP ALB Internal -Page 3 of 7 -Question 2: (The Application Layer) a) If an FTP client is in active mode, what are the two FTP commands (protocol commands) issued by the client when the user issues: ftp> ls [2 marks] b) If an FTP client is in passive mode, what are the two FTP commands (protocol commands) issued by the client when the user issues: ftp> get [2 marks] c) The command netstat is used by a system administrator. Explain the difference between LISTEN and ESTABLISHED states. Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 localhost:1234 *:* LISTEN tcp 0 0 localhost:43000 it046500:20 ESTABLISHED [2 marks] d) How many simultaneous connections does HTTP needs in order to download a single file? How many simultaneous connections does FTP needs in order to download a single file? [2 marks] e) Briefly explain what is a DNS (Domain Name Service) iterated query. Explain why this method is important to keep the scalability of the DNS. [2 marks] 1102/159.334 CP ALB Internal -Page 4 of 7 -Question 3: (The Transport Layer) a) A distributed system uses UDP to transfer files between nodes. You are asked to design a simple reliable protocol to replace it. What are the essential elements that you need to…

  • March 15, 2018
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