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DTS620S - DISTRIBUTED SYSTEMS - 1ST OPP - NOV 2022 |
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nAm I Bl A un IVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTY OF COMPUTING AND INFORMATICS
DEPARTMENT OF COMPUTER SCIENCE
QUALIFICATION: BACHELOR OF COMPUTER SCIENCE, SYSTEMS ADMINISTRATION
QUALIFICATION CODE: 07BACS
LEVEL: 6
COURSE NAME: DISTRIBUTED SYSTEMS
COURSE CODE: DTS620S
DATE; NOVEMBER 2022
PAPER: THEORY
DURATION: 2 HOURS
MARKS: 70 (100%}
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
EXAMINERS
MS ALBERTINA SHILONGO
MODERATOR
PROF. JOSE QUENUM
--
THIS QUESTIONPAPERCONSISTSOF 3 PAGES(Including this front page)
INSTRUCTIONS
1) Answer ALL the questions on the answer scripts provided.
2) Be guided by the number of marks allocated when answering the questions.
3) Write clearly and neatly.
4) Show all your calculations.
5) Number your questions clearly.
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Question 1:
1. What is the main idea of designing a distributed system?
(2)
2. List and explain any four (4) characteristics of distributed systems.
(8)
3. Explain the role of middleware in supporting the development of distributed applications
and services.
(4)
4. Explain why Heterogeneity is unavoidable in distributed systems
(3)
5. Justify why systems in Education, e-commerce, and environment management can be
classified as distributed.
(6)
(23 Marks]
Question 2
1. Explain the concept of independent failure in distributed systems.
(3)
2. Group Communication paradigm routes messages via multicast, using various communication
protocols; at times the message sent is never received by the receiver; why is this the case? (4)
3. If a communication paradigm is synchronous, is it also time-coupled, with an example, explain
the characteristics of this paradigm.
(3)
4. Explain the concept of indirect communication (space and time uncoupling) in relation to the
communication that takes place on Microsoft Teams.
(4)
5. Why is scalability an important feature in the design of a distributed system?
(2)
6. Explain why transparency is a major requirement in a distributed file system.
(3)
7. Differentiate between Concurrency transparency and Location transparency
(4)
8. Many of the information resources that are made available and maintained in distributed
systems have a high intrinsic value to their users. Their security is therefore of
considerable importance. List and explain the 3 components of information resources (6)
9. Discuss how the following security challenges can be experienced in distributed systems. (6)
a) Denial of service attacks:
b) Security of Mobile code:
[35 Marks]
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Question 3
Consider figure 1 below that shows 3 processes (Pl, P2, and P3) executing in a distributed System
with various messages passing between the processes. Assume that initial logical clock values are
all initialized to 0.
1. Using Vector Clock, for each event shown in the figure, list all the packet's logic clocks. (12)
s
P2:
Error!No text of specified style in document.
[12 Marks]
Exam Ends
Total 70 Marks
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