BIT 2303 DISTRIBUTED SYSTEMS1 KCA Past Paper
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: 30 MARKS (COMPULSORY) a) Define the terms Message Passing and Remote Procedure Call, highlighting at least one similarity and one difference. (6 marks) b) By the use of well labeled diagram define the terms a Distributed System and a Centralized System, highlighting the differences. (6 marks) c) Describe the components that make a Distributed System. (6 marks) d) Discuss any four security requirements in a Distributed System, highlighting the threat to each threat. (6 marks) e) Discuss the ring algorithms for conducting elections when the primary server fails (6 marks) QUESTION TWO: 20 MARKS a) By use of a well labeled diagram to describe the element of an RPC mechanism (8 marks) b) By use of diagrams, discuss the similarities between local procedure calls (lpc) and remote procedure calls (rpc) (6 marks) c) Define the term replication (2 marks) d) Discuss the following types of replication (4 marks) i) Active replication ii) Passive replication QUESTION THREE: 20 MARKS a) Differentiate between the NOS and DOS (4 marks) b) Discuss the similarities between Procedure Calls (PC) and Remote Procedure Calls (RPC). (4 marks) c) With the help a diagram illustrate what a message is explaining its structure 7 marks d) Describe the basic file replication protocol (5 marks ) QUESTION FOUR: 20 MARKS a) Define the term file service (2 marks) b) Discuss four properties that a DS resource sharing mechanism must have in order to provide concurrency transparency (8 marks) c) Define the following concept used in synchronization (4 marks) i) Skew ii) Clock drift iii) UTC iv) Internal synchronization d) Describe the Berkeley algorithm for achieving synchronization in clocks within Distributed Systems. (6 marks) QUESTION FIVE: 20 MARKS a) Using an appropriate example differentiate between the following terms used in IPC. (2 marks) i) Idempotent Operations ii) Non-idempotent Operation b) Explain briefly how non-idempotent operations are solved. (4 marks) c) Describe the following type of programmed threats in Distributed Systems and discuss how avert them. (6 marks) i) Trojan horses ii) Logic bombs iii) Trap iv) Viruses d) Using well labeled diagrams, differentiate between synchronous communication and asynchronous communication. (4 marks) e) Describe the following Distributed File Service requirements (4 marks) i) Concurrency ii) Heterogeneity iii) Efficiency iv) Security
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