NIELIT A Level Solved Paper July-2011

July, 2011

A9-R4: DATA COMMUNICATION AND NETWORK TECHNOLOGIES

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 In Quadrature Phase Shift Keying (QPSK) modulation
A) a cosine carrier is varied in phase while keeping a constant amplitude and frequency
B) a sine carrier is varied in phase while keeping a constant amplitude and frequency
C) a cosine carrier is varied in amplitude while keeping a constant phase and frequency
D) a sine carrier is varied in amplitude while keeping a constant phase and frequency

1.2 Frequency Hopping Spread Spectrum (FHSS) is a
A) Spread spectrum RF technology for 4.8 GHz
B) Spread spectrum RF technology for 2.4 GHz
C) Spread spectrum RF technology for 4.8 KHz
D) Spread spectrum RF technology for 2.4 KHz
1.3 Which layer is responsible for flow control with sliding windows and reliability with sequence
numbers and acknowledgments?
A) Transport
B) Application
C) Internet
D) Network Interface
1.4 IPv6 uses ________ bit address, whereas IPv4 uses ________ bit address
A) 128, 32
B) 64, 32
C) 128, 64
D) 256, 128
1.5 Leased line and ISDN are two types of commonly used
A) LAN links
B) Radio Links
C) WAN links
D) Satellite Links
A9-R4 Page 2 of 5 July, 2011
1.6 The GSM is a
A) Packet-switched system that divides each 200kHz channel into eight 25kHz frequency-slots.
B) Circuit-switched system that divides each 250kHz channel into eight 25kHz time-slots.
C) Circuit-switched system that divides each 200kHz channel into ten 20kHz time-slots.
D) Circuit-switched system that divides each 200kHz channel into eight 25kHz time-slots.
1.7 ATM Technology uses the following features
A) Fixed-size cells
B) Connection-oriented service
C) Asynchronous multiplexing
D) All of the above
1.8 When a network layer firewall is used, access to and from a whole network is controlled by
means of a
A) Switch operating at a data link layer
B) Router operating at a network layer
C) Hub operating at a network layer
D) Switch operating at a network layer
1.9 What is the range of addresses in the class C of internet addresses?
A) 192.0.0.0 - 223.255.255.255
B) 240.0.0.0 - 247.255.255.255
C) 128.0.0.0 - 191.255.255.255
D) 224.0.0.0 - 239.255.255.255
1.10 A hypertext link is a
A) Special tag that links one page to another page or resource
B) Special frame that links one page to another page or resource
C) Special header that links one page to another page or resource
D) Special frameset that links one page to another page or resource

2. Each statement below is either TRUE or FALSE. Choose the most appropriate one and ENTER in the ‘tear-off’ answer sheet attached to the question paper, following the instructions therein. (1x10)

2.1 CDMA uses unique spreading codes to spread the baseband data before transmission
2.2 Ipv4 address consists of three parts, The country number(ID), the network number(ID) and
host number(ID).
2.3 Bandwidth is defined as the maximum number of bits that can flow through a network
connection in a given period of time.
2.4 Telnet can be used to connect to virtually any machine irrespective of the fact that the
machine listens on ports or not.
2.5 The term Very Small Aperture Terminal (VSAT) refers to a small fixed earth station that has
the capability to receive as well as transmit signals via the satellite to other VSATs in the
network
2.6 Routing occurs at the Transport layer of the OSI model.
2.7 In both UDP and TCP, check summing is optional.
2.8 When the booting computer sends the unicast ARP request, it places its own hardware
address in both the sending and receiving fields in the encapsulated ARP data packet.
2.9 The standard connector for unshielded twisted pair cabling is an RJ-45 connector.
2.10 Internet Control Message Protocol (ICMP) is used for network error reporting and generating
messages that require attention
3. Match words/phrases in column X with the closest related meaning/word(s)/phrases
in column Y. ENTER in your selection the ‘tear-off’ answer sheet attached to the
question paper, following the instructions therein. (1x10)

X		Y
3.1	Hourglass model	A.	Multicast
3.2	Reservation ALOHA, or R-ALOHA	B.	NFS (Network File System)
3.3	refers  to  the  specifications   for  fiber optic cable carrying Ethernet signals.	C.	10Base2
3.4	The    transmission    of    a    packet    to    multiple destinations in a single send operation	D.	ISO Open Systems Interconnection
3.5	Dynamic Routing	E.	B, D Channels
3.6	is a feature that allows systems   on an internal network to use private IP addresses (such as those in the 192.168.0.0 range) to connect to the Internet using only one “real” IP address.	F.	channel access method for wireless transmission
3.7	is an industry standard means of being able to share entire file systems among machines within a computer network.	G.	IEEE 802.3 Technology
3.8	Transmission Control Protocol (TCP)	H.	BGP
3.9	standard   defines   Ethernet    at   the physical and data link layers of the OSI network model	I.	Network layer
3.10	Token Ring	J.	IBM
		K.	Reliable connection oriented service
		L.	NAT (Network Address Translation)
		M.	10BaseF

4. Each statement below has a blank space to fit one of the word(s) or phrases in the list

below. Choose the most appropriate one and ENTER in the ‘tear-off’ answer sheet attached to the question paper, following the instructions therein. (1x10)

A.	DSSS	B.	DHCP	C.	DNS
D.	Core	E.	Cellular Radio	F.	Wavelength-Division Multiplexing (WDM)
G.	CSMA/CA	H.	TCP	I.	HTTP
J.	LAN	K.	Plastic	L.	Secure Socket Layers (SSL)
M.	X.25

4.1 The ________ protocol, manages access to the wireless medium, to avoid messages
getting lost due to frame collisions.
4.2 Fiber optic cables carry data signal in the form of light. The signal is propagated through
________ by reflection.
4.3 ________ allows a host to obtain an IP address dynamically (or automatically) from servers.
4.4 A secure Web Server uses the ________ technology to establish an encrypted connection
between the Web Server and the client.
4.5 Radio communication based on a network of transmitters each serving a small area known
as a cell is called as ________.
4.6 ________ is a technology which multiplexes a number of optical carrier signals onto a single
optical fiber by using different wavelengths.
4.7 A popular standard for packet-switching networks is ________.
4.8 The reliable transport protocol that is connection oriented is called ________.
4.9 ________ avoids excessive power concentration by spreading the signal over a wider
frequency band.
4.10 Internet system to translate names into IP addresses is known as ________.

PART TWO

(Answer any FOUR questions)

5.
a) Explain the difference between
i) Static versus Dynamic IP Addressing
ii) Guided versus unguided media
iii) UDP versus TCP
b) What is Amplitude Shift Keying (ASK)? What are its merits and demerits? Why ASK
modulation is not being used in wireless systems?
c) What are the primary responsibilities of the physical layer? Mention some of the network
devices that are used in this layer.
(5+5+5)
6.
a) How does TCP handle the flow control problem? Explain it with the help of a diagram
showing the status of sliding window at the different stages?
b) Compute the CRC-4 character for the 1100 0110 1011 01 message using a divisor constant
of 10011.
c) Explain why a message is broken into packets by TCP/IP prior to transmission.
(5+5+5)
7.
a) What is the role of OSPF routing protocol? Explain with the help of an example the algorithm
used under OSPF.
b) Can a computer have 2 DNS names that fall in different top-level domains? If so, give an
example. If not, explain why not.
c) What do you understand by MIME?
(5+5+5)
8.
a) What is VPN (Virtual Private Network)? What is the relationship between VPN and firewalls?
b) Give main difference between encryption and digital signature.
c) “Distance vector protocols do not distribute any topology information; they simply advertise
the next hop to a route, along with a cost.” Discuss the statement.
(5+5+5)
9. Write short notes on any five:
a) Shared and private SSL
b) ATM Technology and Ethernet Technology
c) Some topologies for networks
d) Network Policies
e) Synchronous and asynchronous transmission
f) Circuit switching and packet switching
(5x3)

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