Wednesday, 8 February 2017

NIELIT A Level Solved Paper July-10

A9-R4 : Data Communication Network Technologies (DCN)

July-10 Solved

PART ONE
(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. (1x10)
1.1 What is true in case of CHAP?
A) It uses a three-way handshake
B) It encrypts the process using RC4
C) It repeats the challenge at random intervals
D) It is stronger than Kerberos
1.2 Which of the following is a MUST have for all implementations of IPSec?
A) Security Association
B) Security ID
C) Serial number
D) Version number
1.3 The data communication medium which converts digital signals from a PC into analog signals
that can be transmitted over telephone lines is:
A) Lease Line
B) Switch
C) Modem
D) Router
1.4 Receiving and transmitting signals simultaneously over a wire is called:
A) Simplex Transmission
B) Half Duplex transmission
C) Full Duplex transmission
D) None of the above
1.5 Which one of the following Internetworking devices operates at Physical layer of OSI model?
A) Router
B) Repeater
C) Gateway
D) All of the above

1.6 Which of the following can be an Ethernet Physical address?
A) C4-17-FE-0B-6F-0A
B) 1A-2B-3C-4D-5E
C) 01:02:03:04:05:06:07
D) None of the above
1.7 The length of an IPv6 address is ___ bits long:
A) 32
B) 64
C) 128
D) Variable
1.8 SSL and TLS are similar but different, how?
A) Both create a secure channel between a client and a server. TLS and SSL interoperate
completely.
B) Both create a secure channel between a client and a server. TLS supports older SSL
connections.
C) Both create a plaintext channel between a client and a server. TLS and SSL interoperate
completely.
D) Both create a plaintext channel between a client and a server. TLS supports older SSL
connections.
1.9 Which of the following is not a Shift keying technique?
A) ASK
B) FSK
C) PSK
D) SSK
1.10 SONET is an acronym for:
A) Standard Optical
B) Symmetric Open
C) Standard Open
D) Synchronous Optical

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. (1x10)

2.1 The path that data travels between two computers is called a communication bridge.
2.2 In Broadcast Network a single Channel is shared by all machines on network.
2.3 Bridges cannot identify networks like routers can.
2.4 Phishing mail is a fake e-mail used to trick a user to reveal his/her personal information.
2.5 In cryptography, the encryption/decryption algorithms are public while keys are secret.
2.6 Digital signature is used to provide privacy.
2.7 ATM transmits switches and multiplexes information in fixed-length cells.
2.8 ALOHA communication is ideal for complex networks in which data travels multiple paths.
2.9 OSPF computes the shortest path for a route using Dijkstra’s algorithm.
2.10 A proxy server is used to bypass INTERNET security and parental controls.

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. (1x10)

X
Y
3.1
A Machine that keeps other machines behind it as
Anonymous
A
ADHOC
3.2
Authenticates and encrypts each packet of data stream.
B
DNS
3.3
It is the most widely used cell phone technology
C
GSM
3.4
This protocol is used by outlook express to fetch mails
from the mail server
D
LEASE LINE
3.5
Has a hierarchical structure and is the largest database.
E
PROXY SERVER
3.6
Expensive but secure WAN technology
F
POP
3.7
A wireless network where there is no single master
node or AP
G
CCITT
3.8
Organisation that sets International Communications
standards
H
IPSEC
3.9
Area Covered by the returning signal from the Satellite
I
TDMA
3.10
Channel Access scheme used by most 2G mobile-phone
standards.
J
FOOTPRINT


K
FIREWALLS


L
PUBLIC KEY


M
FDMA


N
WIRELESS

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. (1x10)

A.
NAT
B.
FHSS
C.
QPSK
D.
TCP
E.
PUBLIC
F.
FDDI
G.
ADSL
H.
DHCP
I.
ICMP
J.
SIP
K.
IEEE
L.
FSK
M.
UDP





4.1 ________ is an Internet Engineering Task Force (IETF) standard protocol for initiating an
interactive user session that involves multimedia elements such as video, voice, chat, gaming,
and virtual reality.
4.2 ________ encodes two bits per symbol and has four possible states.
4.3 ________ signal does not stay in one place on the band and it can elude a jammer.
4.4 The host uses ________ to retrieve its IP address and other configuration information from a
specific server.
4.5 The distinguishing characteristic of ________ over other forms of Digital Subscriber Lines is
that the bandwidth is greater in the direction to the customer premises than the reverse.
4.6 ________ is a standard for data transmission on fibre optics and based on Token Ring
Technology.
4.7 The practical solution to impeding exhaustion of IP addresses is ________.
4.8 The Reliable Transport Protocol that is connection oriented is called ________.
4.9 The protocol that is mostly used for trouble-shooting IP networks is called ________.
4.10 A ________ key cryptography approach involves use of asymmetric key algorithms.

(Answer any FOUR questions)

5.
a) What is a single mode and multimode Optical fibre? Name any four advantages of optical fibre
as a communication medium?
b) Draw the layered structure of OSI model and TCP/IP model.
c) Describe briefly Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM)
techniques with relevant diagrams.
(5+5+5)
6.
a) Differentiate between the guided and unguided media? State the four basic types of guided
media?
b) Why is it important for protocols configured on the top of Ethernet to have a length field in their
header, indicating how long the message is? Discuss what kinds of problems arise when two
computers on the same Ethernet share the same MAC (hardware) address.
c) The ASCII character B is transmitted with an even-parity bit appended to it. Illustrate how the
receiver would detect an error.
(5+5+5)
7.
a) What is a Virtual LAN? When should you consider using a VLAN in your network?
b) Describe the functioning of a Router in a network?
c) What is the difference between an Ethernet switch and an Ethernet hub? Which is more
suitable for a network with a high traffic load, a switch or a hub? Explain.
(5+5+5)
8. Write short notes on any three of the following?
a) World Wide Web (WWW)
b) Domain Name System (DNS)
c) Simple Network Management Protocol (SNMP)
d) Modem
(3x5)
9.
a) Why is it essential to restrict the access of wireless network? Mention any three steps to
protect/secure your wireless network.
b) What is VPN? Explain tunnelling with relation to VPN.
c) Mention five good security practices while using a computer system at a cyber cafe.
(5+5+5)