Pune University Question Paper
BE Computer Engineering, Distributed Systems
B.E. (Computer Engineering)
(2003 Course) (410451)
Time : 3 Hours] [Max. Marks :100
Instructions to the candidates:
1) Answers to the two sections should be written in separate books.
2) Neat diagrams must be drawn wherever necessary.
3) Figures to the right indicate full marks.
4) Use of logarithmic tables, slide rule, mollier charts, electronic pocket calculator and steam table is allowed.
5) Assume suitable data, if necessary.
SECTION – I
a) Compare between multiprocessor operating system, multicomputer operating system, network operating system and middleware based distributed systems. 
b) Explain different levels in client server application with suitable example. [
Q2) a) Explain different transparencies in distributed system with suitable examples. 
b) Explain in detail middleware models and services provided by middleware.  c) Explain variations on the client-server model in distributed system. 
Q3) a) Explain how quality of service can be achieved in stream oriented communication. 
b) Explain different forms of communication in message oriented communication. 
Q4) a) Explain general architecture of message queuing system for persistent communication. 
b) Explain different RPC models in detail. 
a) Explain fault tolerant issues in NFS. 
b) Explain principle of log based striping in xFS with diagram. 
c) How Coda solves read-write conflicts on a file that is shared between multiple readers and only a single writer? 
a) Compare the following distributed file systems: Coda, xFS, 
b) Explain the difference between name server and directory server with examples. 
c) How DNS can be used to implement a home based approach to locating mobile hosts? 
SECTION – II
Q7) a) Explain how the causality can be captured by means of vector timestamps. 
b) Explain how NTP (network time protocol) is useful to distribute time over the Internet, also state the features of NTP. 
c) Explain ring algorithm with suitable example. 
a) Compare Centralized, Distributed and Token Ring algorithms of mutual exclusion. 
b) Explain how Lamport timestamp can be used in totally-ordered multicasting. 
c) Compare Cristian and Berkeley algorithms of clock synchronization. 
a) Explain different classes of failures that can occur in the RPC systems. 
b) Consider a Web browser that returns an outdated cached page instead of a more recent one that had been updated at the server. Is this a failure, and if so, what kind of failure? 
Q10) a) Explain n-army problem with possible solution, 
b) In the two-phase commit protocol, why can blocking never be completely eliminated, even when the participants elect a new coordinator? 
c) Explain how the write-ahead log in distributed transactions can be used to recover from failures. 
a) Explain CORBA ORB Architecture.
b) Explain the elements of Grid Computing systems. OR
a) Compare Grid Computing and Cluster computing.
b) Explain different types of Clusters with examples. c) Explain the steps to build CORBA application in brief.