DOEACC Society 2007 Advanced Level Course In Computer Science A9-R3: DATA COMMUNICATION

PART - TWO
(Answer ANY 4 questions)

5.
a) What is the difference ranging from flow control and congestion control?
b) What is reflection? What happens to a beam of light as it travels to a less sense medium? What happens if it travels to a denser medium?
c) How does ionospheric propagation work? Which kinds of users normally use this kind of propagation?
d) What is the difference ranging from network layer delivery and transport layer delivery?
(2+[1+1+2]+4+5)

6.
a) Compare virtual circuit with datagram subnet?
b) How is 1 TDM signal separated into its original components? Consider both implementations of TDM?
c) What procedure is used to prevent a stream of binary data from being misinterpreted as an HDLC flag? discuss ht operation of this procedure?
(5+7+3)

7.
a) Compare fibre optic cable with UTP cable when used as transmission media in LANs.
b) Why is IP not exactly suitable for real time services?
c) Compare and contrast CSMA/CD and token-passing access methods.
d) What is a subnet mask and why is it necessary?
(3+3+4+[2+3])

8.
a) What are the various classes of addresses used in Ipv4? List their ranges in dotted decimal notation.
b) What are the roles of repeaters, bridges, routers and gateways in achieving internetworking? Identify the layers in which they operate.
c) Computing the checksum for the subsequent data frame, obtain the complete transmitted frame bit pattern:
data, D = 11001011011
generator polynomial, G(x) = x4 + x + 1
d)
([2+4]+[4+2+3)

9. Write short notes on any three:
i) VSAT
ii) QPSK
iii) SONET
iv) Spread Spectrum
(3x5)

A9-R3: DATA COMMUNICATION & COMPUTER NETWORKS

NOTE:
1. There are 2 PARTS in this Module/paper. PART 1 contains 4 ques. and PART 2 contains 4 ques..

2. PART 1 is to be answered in the TEAR-OFFANSWER SHEET only, attached to the ques. paper, as per the instructions contained therein. PART 1 is NOT to be answered in the ans book.

3. Maximum time allotted for PART 1 is 1 HOUR. ans book for PART 2 will be supplied at the table when the ans sheet for PART 1 is returned. However, candidates who complete PART 1 earlier than 1 hour, can collect the ans book for PART 2 immediately after handing over the ans sheet for PART ONE.
TOTAL TIME: three HOURS TOTAL MARKS: 100
(PART ONE-40; PART 2 – 60)

Earning:   Approval pending.