代写COMP90015、代写C++，Java编程

日期：2022-11-05 08:48

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.