comp90015代写-COMP90015
时间:2022-11-03
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The University of Melbourne  
COMP90015 Distributed Systems  
Semester 2, 2022 Sample Examination  

School of Computing and Information Systems  
COMP90015 Distributed Systems  
Reading Time: 15 minutes  
Writing Time: 3 hours  
Open Book Status: Open Book – Online.  
Authorized Materials: You are permitted to make use of material available on the Web in  
general, including course notes, recordings, materials on LMS, and research literature and  
websites.  
This paper has 2 pages including this page  
Identical Examination Papers: The examination paper is available as either a PDF or Word  
document. The documents have identical content and differ only in minor formatting ways.  
Instructions to students:  
• The maximum mark for this paper is 60.  
• The examination is worth 60% of the subject assessment.  
• Attempt all questions - partial credit is available.  
• You are required to submit a single document that contains all of your answers. Acceptable  
document formats include PDF, or a Word file. Please include your student number at the top  
of the first page of the document, prepare your answers in the same order as the questions  
given in the exam paper, and number your answers with the same numbering as in the exam  
paper.  
• You may type your answers, include diagrams/images if you wish, and you may draw and  
scan images to include in the document. You may prepare all your answers on paper, using  
handwritten answers if you wish, and simply scan all of your answers into a single PDF  
document and submit that way if you wish. For coding questions, you can just specify the  
file/class name and paste the code as a plain text, or as snapshots in the document. Make  
sure that all scanned material and diagrams/images are clearly legible.  
• You must adhere to the Academic Integrity Declaration. In each of your answers, cite all  
materials that you sourced information from.  
• Unless you have a special time allowance, you have an examination time of 3 hours and 15  
minutes to complete and upload your answers document, for it to be considered "on time".  
After the examination time, you have an additional late submission period of 30 minutes to  
submit your answers document - submissions in this period will be considered "late". The late  
submission period cannot be used as additional exam time. The Subject Coordinator may  
request evidence of technical issues and a late penalty may apply. After this period, you will  
not be able to upload your answers document.  
• You may submit multiple times (unlimited), but only the final (last) submission will be looked  
at for assessment. If the final submission is within the late period, then your submission will  
be considered late, as above. You will not be able to revert to an earlier submission.  

COMP90015 Distributed Systems  
2  

1. [5 Marks] Suppose you need to develop a DNS resolver which only supports  
iterative navigation (starting from the root server) to resolve a given hostname  
to the corresponding IP address. Write the high-level steps (at most 10 lines)  
for the DNS resolver.  

2. [5 Marks] What is mobility transparency? Provide a high-level conceptual  
discussion on how you would extend Network File System (NFS) to enable  
mobility transparency.  

3. [5 Marks] Why symmetric keys are used for traffic encryption instead of  
asymmetric keys? Explain how asymmetric keys are used in digital signatures.  

4. [10 Marks] Write a simple Java RMI program that demonstrates the invocation  
of remote object services. Implement a service which offers dictionary services.  
It should support 3 operations/services (a) “ADD” which adds a new word and  
its meaning to the dictionary; (b) “SEARCH” which returns the meaning of a  
word passed as an argument. (c) DELETE which deletes word passed as an  
argument from the dictionary. Write both server and client programs.  




*** Note, the actual exam is worth 60 marks, and contains ten  
questions each worth 5 marks, and one coding question worth  
10 marks. 
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