UNIVERSITY EXAMINATIONS: 2014/2015
ORDINARY EXAMINATION FOR THE BACHELOR OF SCIENCE
IN INFORMATION TECHNOLOGY
BIT 2303 DISTRIBUTED SYSTEMS
DATE: APRIL, 2015 TIME: 2 HOURS
INSTRUCTIONS: Answer Question ONE and any other TWO
QUESTION ONE
a) Differentiate between the following:
i) Blocking and non blocking semantics [2 marks]
ii) Differentiate between RPC and RMI. [2 marks]
iii) Multiprocessor and multicomputer [3 marks]
iv) Tightly coupled systems and loosely coupled systems. [2 marks]
b) Explain Higher-level and Lower-level protocols of the OSI models. [6 marks]
c) Briefly explain threads as applied in distributed system. [3marks]
d) Briefly explain the mechanisms for implementing Remote IPC. [6 Marks]
e) Discuss the characteristic features of ATM technology that is expected to have an
impact on future distributed systems. [6 Marks]
QUESTION TWO
a) Define process migration, explaining what it involves in a distributed system.
[4marks]
b) Briefly explain four desirable features of a good process migration mechanism.
[4marks]
c) Discuss the methods of achieving mutual exclusion in a distributed system.
[6marks]
d) Discuss the process migration mechanisms, giving the benefits and limitations of each
mechanism. [6 marks]
QUESTION THREE
a) Briefly explain three metrics of a scalable system. [6 marks]
b) Describe the issues in Concurrency and solutions to these concurrency problems.
[6marks]
c) Discuss the following distributed system models
i) Three tier architecture [2marks]
ii) Mobile code [3marks]
iii) Mobile agent [3marks]
QUESTION FOUR
a) Briefly explain the following file models and accessing models
i) Unstructured and structured files [2marks]
ii) Mutable and immutable files [2marks]
iii) Remote service model [2marks]
iv). Data-caching model [2marks]
b) Describe the benefits of file replication in a DFS. [7marks]
c). Identify the file properties that influence fault tolerance. [5marks]
QUESTION FIVE
a) Discuss the algorithms used in clock synchronization. [6marks]
b) Explain the Lamport timestamps, as used in process synchronization. [4marks]
c) With the aid of a diagram discuss the relative benefits and limitations of three
Commonly used models for configuring a distributed computing system. [10marks]
