Computer Science 162 - Spring 2001 - Joseph - Final

Computer Science 162 - Spring 2001 - Joseph - Final - CS162...

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CS162 Final, Spring 2001 CS 162 Final Spring 01 Problem 1 . (22 points total) Short Answer. a. T/F and Why (9 points) Circle the correct answer and provide a short, one-sentence reason for your answer. i) Adding a cache never hurts performance. ii) Unlike public key encryption, using private key encryption requires that the two communicating parties sharing a secret key ahead of time. iii) The optimal place on the disk for directory blocks in the innermost cylinder of the disk. b. (9 points) Assume the queue of disk blocks that the file system must write out contains blocks located on the following cylinders: 45, 18, 20, 10, 50 Assume the disk head just wrote a block on cylinder 15 and is currently over cylinder 16. List the order will blocks be written out with: i) FIFO: ii) Shortest Seek Time First: iii) SCAN / Elevator: c. (4 points) network file systems use server-callback or client-poll validation schemes for cached data. i) Which one does NFS use? ii) Which one does AFS use? Problem 2 . (18 points total) Networking. a. (10 points) Shown below is network configuration for each router's table. The network link marked with an X becomes unavailable. Fill in the final state for each router's table that results after multiple rounds of exchange between the routers. file:///C|/Documents%20and%20Settings/Jason%20Raftery/My%20Documents/U. ..0Science%20162%20-%20Spring%202001%20-%20Joseph%20-%20Final%20Exam.htm (1 of 7)1/27/2007 5:34:23 PM
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CS162 Final, Spring 2001 A Table A B C D E Initial Distance 0 1 2 2 3 Out link - B B B B Final Distance Out link B Table A B C D E Initial Distance 1 0 1 1 2 Out link A - C D D Final Distance Out link C Table A B C D E Initial Distance 2 1 0 2 1 Out link B B - E E Final Distance Out link D Table A B C D E Initial Distance 2 1 2 0 1 Out link B B E - E Final Distance file:///C|/Documents%20and%20Settings/Jason%20Raftery/My%20Documents/U. ..0Science%20162%20-%20Spring%202001%20-%20Joseph%20-%20Final%20Exam.htm (2 of 7)1/27/2007 5:34:23 PM
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CS162 Final, Spring 2001 Out link E Table A B C D E Initial Distance 3 2 1 1 0 Out link C C C D - Final Distance Out link b. (8 points). Your new boss at Megasoft Corporation proposes a new sliding window-based reliable network transport protocol. The protocol works as follows: instead of sending an acknowledgement for eery packet, it only sends an acknowledgement for every 4 packets (by sequence number). Thus ACK #1 is sent when packets with sequence numbers 0-3 have been received. ACK #2 is sent when packets with sequence 4-7 have been received. Acknowledgements do not cover packets from earlier sequence numbers and can be sent out of order (i.e., ACK #2 can be sent when packets with sequence numbers 4-7 have been received successfully,
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This note was uploaded on 05/17/2009 for the course CS 162 taught by Professor Kubiatowicz during the Spring '02 term at University of California, Berkeley.

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Computer Science 162 - Spring 2001 - Joseph - Final - CS162...

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