DOEACC Exam Paper - Data Communication and Networks

Get the Solved Question Papers of DOEACC Society 'A' Level - A9-R3 Data Communication and Networks of July 2006.

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(PART ONE – 40; PART TWO – 60)
(Answer all the questions)

1. Each question below gives a multiple choice of answers. Choose the most
appropriate one and enter in the "tear-off" answer sheet attached to the question
paper, following instructions therein. (1 x 10)
1.1 Which one of the following is a balanced interface?
A) RS-232C
B) RS-423C
C) RS-449
D) RS-422
1.2 A crossbar switch having n input lines and n output lines (i.e. n full duplex lines) has
following number of intersections.
A) n
B) 2n
C) n2
D) 2n2
1.3 Video on demand, Live television, from many sources, full motion multimedia, electronic
mail is offered by
A) X.25
B) Frame Relay
1.4 The device operating at Data link layer is
A) Bridge
B) Router
C) Repeater
D) None of the above
A9-R3 Page 1 of 5 July, 2006
1.5 Flow control is the mechanism to regulate the flow of information, so that a fast host
cannot overrun a slow one. This is the function of the following OSI Layer
A) All Layers
B) Physical Layer
C) Transport Layer
D) Application Layer
1.6 The T1 carrier corresponding to time division multiplexing consists of following number
of voice channels
A) 24
B) 12
C) 20
D) 32
1.7 In Cellular Mobile Communication handoff means
A) to disturb the signal
B) to disturb the antenna
C) to switch to a new channel when call is in progress
D) to switch off the MTSO
1.8 GSM stands for
A) Good Service Management
B) Global Service Management
C) Good Sender Memory
D) Global System for Mobile Communications
1.9 Dual cable and signal cable are the two types of
A) Broadband networks
B) Baseband networks
C) Radio networks
D) Satellite networks
1.10 TELNET, FTP, SMTP, Protocols fall in the following layer of OSI reference model
A) Transport Layer
B) Internet Layer
C) Network Layer
D) Application Layer

A9-R3 Page 2 of 5 July, 2006
2. Each statement below is either TRUE or FALSE. Choose the most appropriate one
and ENTER in the "tear-off" sheet attached to the question paper, following
instructions therein. (1 x 10)
2.1 The cells used in Mobile Communications are triangular in shape.
2.2 X.25 is based on virtual circuit.
2.3 Two commonly used data link layer standards are RS-232-C and its successor RS-449.
2.4 PCM is not a common digital modulation method.
2.5 The ATM cells are 64 bytes long.
2.6 IP is a best-effort connectionless protocol.
2.7 The most popular network system in the PC world is Novell Netware.
2.8 The remote controls of TVs, VCRs and Stereo use Radio waves.
2.9 A new development in the communication satellite world is development of low cost
microstations, sometimes called VSATs (Very Small Aperture Terminals).
2.10 Routing and switching in frame relay are performed by the data link layer.
3. Match words and phrases in column X with the closest related meaning/
word(s)/phrase(s) in column Y. Enter your selection in the "tear-off" answer sheet
attached to the question paper, following instructions therein. (1 x 10)
3.1 Total Internal Reflection A. A simplex protocol
3.2 Cryptography B. Stop and wait protocol
3.3 Echo suppressor C. Fiber optics
3.4 Codec D. Security
3.5 Go back n E. Telephone System
3.6 Multiple access protocols F. Local loop
3.7 Logical Link Control G. Sliding window protocols
3.8 Polling H. IEEE 802.3
3.9 Firewall I. IEEE 802.4
3.10 Flow control & buffering J. Frame Relay
L. IEEE 802.2
M. Satellite Networks
N. Internetworking
O. Transport Layer

A9-R3 Page 3 of 5 July, 2006
4. Each statement below has a blank space to fit one of the word(s) or phrase(s) in
the list below. Enter your choice in the "tear-off" answer sheet attached to the
question paper, following instructions therein. (1 x 10)
A. Cryptography B. HDLC C. Modem
D. Star topology E. Analog Signal F. Framing
G. Distributed queue dual bus H. CDPD I. Routing Algorithm
J. Congestion K. Circuit L. SNA
M. 1 MHz N. Diffraction grating O. CDMA
P. Traffic shaping Q. Crash Recovery R. Management Information
4.1 ________ is one of the data link layer design issues.
4.2 ________ is IEEE standard 802.6.
4.3 ________ is a packet switched digital datagram service.
4.4 ________ is that past of the Network Layer software responsible for deciding which
output line an incoming packet should be transmitted on.
4.5 When too many packets are present in the subnet, performance degrades this situation
is called ________.
4.6 In WDM, an optical system uses a(n) ________.
4.7 ________, avoids time synchronization problem and also the channel allocation
4.8 ________ is an approach to congestion management.
4.9 ________ is an element of transport protocol.
4.10 The collection of all possible objects in a network is given in a data structure called the

A9-R3 Page 4 of 5 July, 2006

(Answer any FOUR questions)

a) Explain with the help of a neat labelled diagram the B-ISDN ATM reference Model.
b) Explain with the help of a neat labelled diagram the ISO-OSI Model and the function of
its various layers.
c) What are the different classes of addresses used in IPv4? List their ranges in dotted
decimal notation.
a) With respect to transmission media, compare Fiber Optics and Copper Wire.
b) Explain the concept of framing with respect to Data Link Layer.
c) Briefly explain the High-Level Data Link Control (HDLC) protocols with neat labelled
a) Compare the IEEE standards 802.2, 802.3, 802.4, 802.5 and 802.6 briefly.
b) Explain the difference between pure ALOHA and slotted ALOHA and draw diagrams for
c) What is high speed LANs? Describe briefly the various types of High-speed LANs used
in computer communication networking.
a) Explain the concept of IP protocols and addresses, subnets and Internet Control
Protocols for the network layer in the Internet.
b) What are Routing Algorithms? Explain flooding, the optimality principle and shortest
path routing.
c) What basic functions does a communication satellite perform? Give a good reason why
up-link and down-link frequencies are not same. Why are earth dish antenna are
generally parabolic in shape?
9. Write short notes on any three:
a) GSM
c) Novell Netware
d) Firewalls

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