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DTS620S - DISTRIBUTED SYSTEMS - 2ND OPP - JAN 2020 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF COMPUTING AND INFORMATICS
DEPARTMENT OF COMPUTER SCIENCE
QUALIFICATION: BACHELOR OF COMPUTER SCIENCE (COMMUNICATION NETWORKS)
QUALIFICATION CODE: 08 BCHC
LEVEL: 6
COURSE: DISTRIBUTED SYSTEMS
COURSE CODE: DTS620S
DATE: JANUARY 2020
SESSION: THEORY
DURATION: 2 HOURS
MARKS: 70
SECOND OPPORTUNITY/SUPPLEMENTARY EXAMINATION QUESTION PAPER
EXAMINER:
MODERATOR:
DR. ATTLEE M. GAMUNDANI
PROF JOSE QUENUM
THIS QUESTION PAPER CONSISTS OF 1 PAGE
(Excluding this front page)
INSTRUCTIONS
Answer ALL the questions.
Write clearly and neatly.
Begin each question on a new page.
Number the answers clearly as per the question paper numbering.
Marks/Scores per question paper are given in [ ].
NUST examination rules and regulations apply.
PERMISSIBLE MATERIALS
1. Scientific Calculator
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Question 1
(a) Give three types of hardware resources and three types of data or software resources that
can usefully be shared. Give examples of their sharing as it occurs practically in distributed
systems [12 marks].
(b) Give and explain any two distributed file system goals [4 marks].
(c) Explain how the use of P2P techniques and Agents, support scalability in distributed systems
design? [4 marks].
Question 2
(a) Given these five security mechanisms that can be used to implement security policies in
distributed systems i.e. encryption, digital signatures, authentication, authorization and
auditing. Select any three and explain how they can be implemented /6 marks].
(b) Where exactly should security mechanisms be applied in a distributed system? Give
practical examples in your answer [6 marks].
(c) Explain with some examples the relationship between total ordered multicast and
distributed consensus? [4 marks].
(d) Highlight and expand on any two pros of active replication compared to passive replication
[4 marks].
Question 3
(a) Explain some of the problems that can be encountered in a distributed system due to RPC
and RMI use for provisioning of transparency [4 marks].
(b) Distributed multimedia applications place considerable demands on the underlying
distributed infrastructure, how? (6 marks].
(c) Imagine a Web server that maintains a table on which client IP addresses are mapped to the
most recently accessed Web pages. When a client connects to the server, the server looks
up the client in its table, and if found, returns the registered page. In your opinion, is this
server Stateful or Stateless? Present an argument to support your opinion [6 marks].
(d) Give and explain any two communication paradigms in distributed systems [4 marks].
Question 4
(a) What ideas or facts show the challenges imposed by areas such as multimedia, mobility and
multiplicity and the implications that this has for distributed systems design? [6 marks].
(b) Can you defend the rationale for the emergence of component-based middleware? [4
marks].
###** END OF EXAMINATION PAPER*****
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