UNIVERSITY EXAMINATIONS: 2010/2011
SECOND YEAR EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE IN INFORMATION TECHNOLOGY
BIT 2303: DISTRIBUTED SYSTEMS
DATE: AUGUST 2011 TIME: 2 HOURS
INSTRUCTIONS: Answer question ONE and any other TWO questions
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. [3 Marks]
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. [4 Marks]
b) Briefly explain four desirable features of a good process migration mechanism. [4 Marks]
c) Discuss the methods of achieving mutual exclusion in a distributed system. [6 Marks]
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. [6 Marks]
c) Discuss the following distributed system models
i. Three tier architecture [2 Marks]
ii. Mobile code [3 Marks]
iii. Mobile agent [3 Marks]
Question Four
a) Briefly explain the following file models and accessing models
i) Unstructured and structured files [2 Marks]
ii)Mutable and immutable files [2 Marks]
iii) Remote service model [2 Marks]
iv) Data-caching model [2 Marks]
b) Describe the benefits of file replication in a DFS. [7 Marks]
c) Identify the file properties that influence fault tolerance. [5 Marks]
Question Five
a) Discuss the algorithms used in clock synchronization. [6 Marks]
b) Explain the Lamport timestamps, as used in process synchronization. [4 Marks]
c) With the aid of a diagram discuss the relative benefits and limitations of three commonly used
models for configuring a distributed computing system. [10 Marks]
