CompNetMidtermFall08

CompNetMidtermFall08 - EPFL-logo Midterm - Computer...

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EPFL-logo Midterm - Computer Networks Prof. J.-P. Hubaux and Dr. M. H. Manshaei November 4, 2008 Duration: 2 hours, closed book. Please write your answers on these sheets, at the end of each question; use extra sheets if necessary (put your name on them). You may write your answers in English or in French. The total number of points is 40. This document contains 19 pages. Student First name: Last name: Division: 2 Communication Systems 2 Computer Science 2 Other (mention it): . . . . . . . . . Year: 2 Bachelor Year 2 2 Bachelor Year 3 2 Other (mention it): . . . . . . . . . (answers to the questions are shown in italic and blue)
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1 Short questions (5 points) For each question, please circle a single best answer . 1. What are three common HTTP 1.1 message method fields? (a) GET, HTML, POST (b) GET, PUT, HTML (c) GET, UPLOAD, HTML (d) GET, POST, PUT (e) None of the above. GET, POST, PUT 2. Given that the requested information is not available at any intermediate databases, a purely recur- sive DNS query from a requesting host would follow the path: (a) Root name server, local name server, authoritative name server. (b) Authoritative name server, root name server, host name server. (c) Local name server, root name server, local name server, authoritative name server. (d) Local name server, root name server, TLD name server, authoritative name server. (e) None of the above. Local name server, root name server, TLD name server, authoritative name server. 3. The request line of text sent to an HTTP 1.1 server by a client for the URL ”http://epfl.ch/class/compnet2008” is: (a) GET /class/compnet2008/ HTTP/1.1 (b) HTTP/1.1 GET http://epfl.ch/class/compnet2008/ (c) GET epfl.ch/class/compnet2008/ HTTP/1.1 (d) HTTP/1.1 GET www.epfl.ch/class/compnet2008/ GET /class/compnet2008/ HTTP/1.1 4. A router typically handles the following layer in the ISO/OSI reference model: (a) Network (b) Link (c) Routing (d) Forwarding Network 5. Consider the following Java application: socket = new DatagramSocket(12345); while (true) { socket.receive(packet); } What happens if two instances of this application are run simultaneously on one machine and 4 UDP segments arrive at port 12345? 2
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(a) Both instances receive all 4 segments. (b) One instance receives all 4 segments. (c) Some segments are received by one instance, other segments are received by the other in- stance. (d) One instance receives segments 1 and 3, the other receives segments 2 and 4. One instance receives all 4 segments. 6. Assume out is a DataOutputStream created from a connected TCP socket and message is a String. We execute: out.writeBytes(message); How many TCP segments are sent and received as a result? (a) sent: 1, received: 0 (b) sent: 1, received: 1 (c) sent: n , received: 0, where n N (d) sent: n , received: 1, where n N (e) sent: n , received: m , where n,m N sent: n , received: m , where n,m N 7. Which one is the UDP checksum of the following three 16-bit words? w 1
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This note was uploaded on 01/09/2012 for the course CS cs464 at Bilkent University.

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CompNetMidtermFall08 - EPFL-logo Midterm - Computer...

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