UGC NET - Unit 7 (INFORMATION TECHNOLOGY)

UNIT – 7
INFORMATION TECHNOLOGY
Vinod
libtejavino@gmail.com

INTRODUCTION TO INFORMATION
TECHNOLOGY
•The term computer has been borrowed from compute that
means- to calculate.
•Where as, initially computers were used to perform
arithmetic calculations at fast speed, Now they are
used in every field.
•Computer is an electronic device, which takes input from
the user, performs calculations and gives out the
result.
•It is also said that computer is a electronic data processor,
because it can receive, store, process and retrieve any
kind of data.

DEFINITION OF COMPUTER
HIGH SPEED
ELECTRONIC
DEVICE
TAKING AN
INPUT
PROCESS
GIVING
OUTPUT

CHARACTERISTICS OF A COMPUTER
Speed
Accuracy
Diligence
Versatility
Stores
Data
Dumb
It has no
emotions

APPLICATION OF COMPUTERS
In applications like Word-processor, Calculations, Games And In
Domestic Applications
For preparing mark sheets and to correct examination papers
In Banking Transactions through out the world
In monitoring millions of phone calls and in keeping lines of
COMMUNICATION
Using computerized technology in Telephone Exchanges
In Railway/Airway Reservations for journey to places thousands of
kilometers away
In Monitoring Life Support Systems in medical equipments and in
diagnosing and curing diseases

STRUCTURE OF COMPUTER
•Controls the operation
of the computer and
performs its data
processing functions.
Often simply referred to
as processor
Central
Processing Unit
(CPU):
•Stores data
Main Memory:
•Moves data between
the computer and its
external environment
I/O Unit:
• Some mechanism that
provides for
communication among
CPU, main memory,
and I/O unit
System
Interconnection:

HISTORY & DEVELOPMENT OF COMPUTERS
•In olden days we calculate using
our fingers. Even today we learn
calculation using our fingers.
•In this process of learning, different
methods are invented to do the same
faster and accurately.
•Let us have a look on some early
computing machines

EARLY COMPUTING MACHINES AND
INVENTORS
Abacus
Slide Rule
Pascaline
Arithmetical
Replica
Arithometer
Differential
Engine
Punched
Cards
Electronic
computers
Mark-
I

GENERATIONS OF COMPUTERS
First
Generation
1940-1956 Vacuum Tubes
Second
Generation
1956-1963 Transistors
Third
Generation
1964-1971
Integrated
Circuits (IC)
Fourth
Generation
1971 -Present Microprocessors
Fifth
Generation
Present and
Beyond
Artificial
Intelligence
(AI)

ANATOMY OF A COMPUTER
Source: NIOS Computer Science

CENTRAL PROCESSING UNIT
 The CPU (Central Processing Unit) is the brain
of the system. It executes all the program code
from the operating system and the applications
you run, and does most of the calculating and
processing of data

MAIN MEMORY
• The Main Memory (MM) consists of magnetic or electronic
components, which store the information needed by the
computer.
• Random Access Memory or RAM is the memory that the
computer uses to temporarily store the information as it is
being processed. One of the first home computers used 64
KB, Now we having 2 to 4 GB RAM
• Most of the Main Memory is erasable and may be changed
at will, some memory is used to store constants and often-
used utility programs and is not erasable by the CPU, and
such memory is called Read Only Memory (ROM). eg.
Operating Systems

INPUT/OUTPUT DEVICES
The I/O devices are the computer's link with
the outside world.
The Input Unit consists of one or more
devices. There are a number of devices that
perform the function of input devices.
The Output Unit converts the binary data into
a form that users can understand

Source: infovisual.co

PROGRAMMING LANGUAGE
 Programming languages are used in computer
programming to implement algorithms.
 Most programming languages consist of instructions
for computers.
 A programming language is a formal language, which
comprises a set of instructions that produce various
kinds of output.

TYPES OF LANGUAGE

TOP COMPUTER LANGUAGES

INFORMATION REPRESENTATION AND STORAGE
 Digital computer represents all information
using the binary numeral system. Text,
numbers, pictures, audio, and nearly any other
form of information can be converted into a
string of bits, or binary digits, each of which has
a value of 1 or 0
 A bit refers to a digit in the binary numeral
system (base 2). For example, the number
100101 1 is 7 bits long

BINARY DIGIT
 Binary digits are almost always used as the basic
unit of information storage and communication in
digital computing and digital information theory.
 Claude E. Shannon first used the word bit in a
1948 paper. He attributed its origin to John W.
Tukey, who had written a Bell Labs memo in 9
January 1947 in which he contracted "binary digit"
to simply "bit“.
 Vannevar Bush had written in 1936 of "bits of
information" that could be stored on the punch cards
used in the mechanical computers of that time.

UNIT:
The bit, as a unit of information, is the
amount of information carried by a
choice between two equally likely
outcomes.
The name bit is mostly used when
discussing data capacity,
emphasising the storage of data as in
dividual binary digits.
A byte is a collection of bits, originally
variable in size but now almost always
eight bits

Credit: www.ccgscomputerscience.co.uk

BINARY SYSTEM
 The Binary System of numeration is the simplest
of all positional number systems. The base - or
the radix - of the binary system is 2, which means
that only two digits – 0 and 1 - may appear in a
binary representation of any number.
 Computer memory comprises small elements
that may only be in two states - off/on - that are
associated with digits 0 and 1. Such an element
is said to represent one bit - binary digit.
 Binary numbers are written with only two
symbols - 0 and 1. For example, a = 1101.

QUICK RECAP
 The first electronic computer - ENIAC that stood
for Electronic Numerical Integrator And
Calculator - was built in 1946 at the University
of Pennsylvania, but the invention of the binary
system dates almost 3 centuries back.
 Gottfried Wilhclm Leibniz (1646-1716), the co-
inventor of Calculus, published his invention in
1701 in the paper ‘Essay d'une nouvelle
science des nombres’ that was submitted to the
Paris Academy.

NUMBER SYSTEMS IN COMPUTER

AMERICAN STANDARD CODE FOR
INFORMATION INTERCHANGE (ASCII)
 ASCII is a character encoding standard for
electronic communication.
 ASCII is the traditional name for the encoding
system; the Internet Assigned Numbers
Authority (IANA) prefers the updated name
us-ascii, which clarifies that this system was
developed in the US and based on the typographical
symbols predominantly in use there.
 ASCII is one of the IEEE* milestones.
* Institute of Electrical and Electronics Engineers

INDIAN SCRIPT CODE FOR
INFORMATION INTERCHANGE (ISCII)
 ISCII is a coding scheme for representing
various writing systems of India. It encodes the
main Indic scripts and a Roman transliteration.
 The supported scripts are: Assamese, Bengali
(Bangla), Devanagari, Gujarati, Gurmukhi,
Kannada, Malayalam, Oriya, Tamil, and Telugu.
 ISCII has not been widely used outside certain
government institutions and has now been
rendered largely obsolete by Unicode.

UNICODE
 Unicode is a computing industry standard for
the consistent encoding, representation, and
handling of text expressed in most of the
world's writing systems.
 The standard is maintained by the Unicode
Consortium, and as of May 2019 the most
recent version, Unicode 12.1
Contains a repertoire of
37,994 characters covering 150
modern and historic scripts, as
well as multiple symbol sets
and emoji.

COMMUNICATION
Communication is a process of sharing
ideas, information, and messages with
others at a particular time and place.
Communication is a vital part of personal
life and is also important in business,
education, and any other situation where
people encounter each other.
Communication between two people is an
outgrowth of methods developed over
centuries of expression

WHAT IS COMMUNICATION AND WHY
• Communication is the transfer of data or information from
one device to another device via some form of transmission
medium.
• Based on the communication medium we can estimate the
time it is going to take to transfer data/information.
• Different types of medium are available for communication;
some of them are Twisted-Pair cable, Coaxial cable, Fiber-
Optic cable etc.
• Currently the trend is on Wireless Technology for
communication, like Cellular phones, walkic-talks, pagers etc.
wireless communication internally uses Radio waves or
Microwaves or Infrared etc.

ROLE OF COMMUNICATION SYSTEMS
Communication through distance
(transmission) or in time (storage)
Adapt the information to the physical
channel (analog/digital and other conversion)
Hide unwanted properties of the physical
channel from the users (e.g. error control)
Reliable, secure, and efficient
Flexible & Simple implementation
Deliver information from sources to destinations
through physical channels

CHARACTERISTICS COMMUNICATION
 The communicating devices must be a part of a
communication system made up of a combination of
hardware and software.
 The effectiveness of the communications systems
depends on the following characteristics.
Delivery
AccuracyTimeliness

COMPONENTS OF COMMUNICATION
Sender Ideas Encoding Channel Receiver Decoding Feedback

COMMUNICATION SYSTEMS
The development of
computer networks
was started when
computers became
faster, more-
powerful and
smaller.
In the 1960’s the
Advanced
Research Projects
Agency (ARPA) of
the U.S.
Department of
Defence
Along with
researchers
working on
military projects at
research centres
and universities
across the country,
developed a
network called the
ARPANET

TELECOMMUNICATION NETWORKS
•Modern telecommunication started with telegraph
network followed by the telephone network.
•Since the connections are established by switching in a
telephone network and the network is open to public, it is
called Public Switched Telephone Network (PSTN).
•When digital computers came about, a new class of
networks, known as data networks were developed to
support computer interconnections.
•The data network has today evolved as Internet.

INTEGRATED SERVICES DIGITAL NETWORK
(ISDN)
 With the maturing of digital technology, a further
advanced telecommunication network called
Integrated Services Digital Network (ISDN)
 ISDN is capable of supporting all types of services
like telephony, facsimile, data transfer and video
transmission.
 We have three major classes of telecommunication
networks in operation:
Telephone
Network
(Landline and
Mobile)
Data Network
(Internet)
Integrated
Services Digital
Network
(ISDN).

TELEPHONE NETWORKS
 Technique or procedure that has evolved in the
last 120 years from a number of giant
corporations is capable of working with each
other.
 With the evolution of mobile communications
predominantly for voice communication, the
telephone network may be viewed in two
different classes
Landline
Networks
Mobile
Networks

LANDLINE NETWORKS
 Landline telephony was born in March 1876 when
Alexander Graham Bell demonstrated long
distance voice communication over a pair of wires.
 In 1877, Operator manned Switching Systems were
set up with the subscribers connected to the operator
switchboard giving birth to the concept of telephone
networks.
 Automatic Switching Systems were invented and
put into operation by early 1890s.
 A powerful application of touch-tone dialling is the
data in voice answer (DIVA) system.
 This system of digit dialling and voice response is also
popularly known as Interactive Voice Response
System (IVRS).
Pulse Dialling
Dual Tone Multi-Frequency

MOBILE NETWORKS
 Mobile communication per se was first introduced in 1946
in USA to support Defence.
 Early systems used a central radio station with a large
antenna mounted at a high point, like a hill, which
radiated high power to cover the entire target area within
which mobility was supported.
 Personal Mobile System (PMS) is based on cellular
communication principle in which a distributed network of
smaller radio stations, called base stations (BS)
 The first generation cellular system went into operation
in 1983 in the United States and was known as advanced
mobile phone system (AMPS).
 European standards are known as Global System for
Mobile (GSM) communications standards. India adopted
GSM standards in 1992. Digital cellular systems like GSM
are called second-generation systems

MOBILE NETWORKS
Credits: PHD Media & iCharts.Net

NEED OF INTERNET
• The main reason
is that each
computer
network is
designed with a
specific purpose.
• Eg. LAN is used
to connect
computers in a
smaller area,
and it provides
fast
communication.
• A Computer can
communicate
with the
computers
attached to the
same network,
because they are
inter-
compatible.
• As more and
more
organisations
had multiple
computer
networks, this
became a major
issue. As a
result, the
concept of
internetworking
(internet) came
into being.
• This means that
there should be
a network of
all physically
separate
networks.

NEED OF PROTOCOLS / STANDARDS
 All Communication need to follow a protocol.
 Protocol is nothing but a convention or standard.
 Eg. Green Signal/Flag and Train
 If the speaker speaks too fast, the listener will
say go-slow to understand. Just like that,
 In Computer World if the receiving computer is
not fast enough, and cannot hold any more data,
it requests the sender to wait or control the
transfer by slowdown.

TCP/IP LAYERS AND PROTOCOLS
 To provide the set of rules and standardization
among the different computer networks.
•International
Standards
Organization
(ISO)
•In 1984
Created a
Model
•Open System
Interconnection
(OSI)

OPEN SYSTEM INTERCONNECTION (OSI)

OPEN SYSTEM INTERCONNECTION (OSI), TCP/IP MODEL AND PROTOCOL
SUITE

INTERFACE LAYER OR (PHYSICAL + DATA LINK
LAYER)
 The physical layer deals with the hardware level
like, transmission media, connections and the voltage
for digital signals.
 The data link layer deals with media access and
control strategies, frame format etc.
INTERNET LAYER OR NETWORK LAYER
 The Internet layer is an important layer in the
protocol suite.
 At this layer, TCP/IP supports Internetworking
Protocol (IP). IP is a host-to-host protocol.
 Ensuring maximum efficiency, TCP/IP supports four
other protocols: ARP, RARP, ICMP and IGMP in this
layer.

PROTOCOL (CONT)
Address Resolution Protocol (ARP)
•On a LAN, each machine is identified with a unique physical address
imprinted on the network interface card. ARP is used to find the
physical address of a machine when its IP address is known.
Reverse Address Resolution Protocol (RARP)
•It is used to find the IP address of a machine when its physical address
is known. It is used when a diskless computer is booted or a computer
is connected to the network for the first time.
Internet Control Message Protocol (ICMP)
•IP is unreliable are best effort delivery. In case of failures ICMP is used
to send notifications to the sender about packet problems. It sends
error and query messages.
Internet Group Message Protocol (IGMP)
•It is used for multicasting, which is transmission of a single message to
a group of Recipients.

TRANSPORT LAYER
 TCP/IP supports two protocols: TCP, UDP, IP is
host-to-host protocol, which can deliver the
packet from one physical device to another
physical device.
•It is simpler of the two protocols. It does not
provide reliability. It is, therefore faster, and
using for applications in which delay is
intolerable (in case of audio and video).
User
Datagram
Protocol (UDP)
•TCP is reliable, connection-oriented protocol.
By connection oriented, we mean that a
connection must be established between both
ends before either can transmit data. It ensures
that communication is error-free and in
sequence.
Transmission
Control
Protocol (TCP)

APPLICATION LAYER
It allows the
user to run
various
applications
on Internet.
These
applications
are File
Transfer
Protocol
(FTP), remote
login
(TELNET),
email
(SMTP),
WWW
(HTTP).
The session
layer of OSI
model is
almost
dropped in
TCP/IP.
Whenever we
work on the
Internet we
use most of
these
protocols.
For example
when use are
surfing or
browsing the
Internet
websites
actually you
are using
WWW.

ANALOG AND DIGITAL COMMUNICATION
 Communication from a source to a destination,
that is, from one computer to another or from one
device to another, involves the transfer of
information from the sender to the receiver.
 The transfer of data from one machine to another
machine such that, the sender and the receiver both
interpret the data correctly is known as Data
Communication.
 Broadly the data communication can be divided into
two types Analog and Digital. As you may know that
signals carry the data for communication.
 Classification of Analog and Digital is based on the
signals which are used for data transfer.

ANALOG SIGNAL
 We mostly use analog signals in our day-to-day life.
 Whatever we are talking meaning voice signals,
Radio and TV broadcasting signals, Electricity
signals, Sunlight or other lights signals, all are
nothing but examples of Analog signal.
 Analog Signals get weaker with the distance
therefore, in long distance communication like
telephones, radio and TV communication we use a
device named “Amplifiers”.
 Amplifiers amplify noise along with the
original signal.

DIGITAL DATA TRANSMISSION
 Computers are digital machines because at their
most basic level they can distinguish between
just two values, 0 and 1, or off and on, or high
and low voltage as depicted in below pic.
 All data that a computer processes must be
encoded digitally, as a series of zeroes and ones.
 A hardware device called Repeater is used to
regenerate the digital signal. The repeater
measures the signal values at regular intervals to
recognise the 0’s and 1’s in the signal and
regenerates them.

DATA COMMUNICATION MODES
 Data can be transmitted from Source to Destination
in a number of ways. The different modes of data
transmission are outlined as follows:
Asynchronous
SynchronousIsochronous
Simplex
Half
Duplex
Full
Duplex

ASYNCHRONOUS COMMUNICATION
 Controlling the timing of operations by the use of
pulses sent when the previous operation is
completed rather than at regular intervals.
 Each frame begins with a start bit that enables
the receiving device to adjust to the timing of the
transmitted signal.

SYNCHRONOUS COMMUNICATION
 Instead of sending single character or few bit we
can send a group or block of data at once, and
this methods is called synchronous
communication.

ISOCHRONOUS COMMUNICATION
 This is another alternative mechanism for data
transmission, which combines the approaches
of asynchronous and synchronous
communications.

SIMPLEX COMMUNICATION
 This is one of the simplest techniques for data
communication, in which we have one
permanent sender and permanent receiver.
 In Simplex transmission, at any point of time one
of the communicating devices can only send
data, whereas the other can only receive it.
 Can you think about some example?

HALF DUPLEX COMMUNICATION
 As we know data communication is more about
exchanging and sharing data, which may not be
fulfilled by the simplex communication.
 Direction of the data one at a time like
A to B or B to A

FULL DUPLEX COMMUNICATION
 The Transmission of data in two directions
simultaneously.

COMMUNICATION CHANNELS
 One of the most common ways to transport data
from one computer to another is to write them
onto magnetic tape or floppy disks, physically
transport the tape or disks to the destination
machine, and read them back in again.
 Cable is the medium through which information
usually moves from one network device to
another.
 There are several types of cable, which are
commonly used with LANs.

TWISTED PAIR CABLE
 Twisted pair cable comes in two varieties:
unshielded twisted pair and shielded twisted
pair.
 Unshielded twisted pair (UTP) is the most
popular and is generally the best option for small
networks UTP cables contain four twisted-pairs
(Orange, Green, Blue & Brown) enclosed in a
common sheath.

COAXIAL CABLE
 Another common transmission medium is the
coaxial cable. It has better shielding than twisted
pairs, so it can span longer distances at higher
speeds.
 A coaxial cable consists of a stiff copper wire as
the core, surrounded by an insulating material.
The insulator is encased by a cylindrical
conductor, often, as a closely woven braided
mesh. The outer conductor is covered with a
protective plastic sheath.

OPTICAL FIBER
 Fiber Optic cabling consists of a center glass core
surrounded by several layers of protective materials.
 It transmits light rather than electronic signals
eliminating the problem of electrical interference.
 Fiber optic cable has the ability to transmit signals
over much longer distances than coaxial and twisted
pair.
 It also has the capability to carry information at
vastly greater speeds.
This capacity broadens
communication possibilities
to include services such as
video conferencing and
interactive services

COMMUNICATION DEVICES
• A Communications device is a hand-held or wearable
device which is enables Communication.
• There are several communication devices used in data
communication. In the sender and receiver computers,
we should have Network Interface Card and Modem
before connected to the Internet connection.
• There are many other devices being used at different
levels and in different types of networks.

NETWORK INTERFACE CARD (NIC)
 It connects the computer to the cabling, which in
turn links all of the computers on the network
together as shown in figure

REPEATER
 It is an electronic device that receives a signal
and retransmits it at a higher level or higher
power, or onto the other side of an obstruction so
that the signal can cover longer distances
without degradation

HUB
 A hub is a device used to connect a PC to the
network.
 The function of a hub is to direct information
around the network, facilitating communication
between all connected devices, means A hub
contains multiple ports. When a packet arrives at
one port, it is copied to all the ports of the hub.
 Hubs can improve performance, especially for
bursty traffic and large file transfers.
 However, total bandwidth remains fixed; as
network traffic grows, performance suffers and it
does not reduce collisions

SWITCH
 A switch is a data-link layer network device that
forwards frames using MAC (Media Access Control )
addresses in the header of frames.
 It is used to improve network performance by
segmenting the network and creating separate
collision domains. It can also reduce competition for
bandwidth.
 During new installations switches should be used
instead of hubs as they are more effective and provide
better performance.
•A switch which is often,
termed a ‘smart hub’.
•With switching, each
connection gets “dedicated
bandwidth” and can operate
at full speed.

BRIDGE
•The main network device found at the data link layer is a
bridge, mainly used for connecting two network or
local area networks.
•This device works at a higher layer than the repeater and
therefore is a more complex device.
•This means that the amount of traffic on the medium can
be reduced and therefore, the usable bandwidth can be
increased
•Bridges are store and forward devices to provide error
detection

HUB VS BRIDGE VS SWITCH
• Hub is really a repeater
• A Message sent by one host is sent to all other hosts.
• One of the simplest ways to create a network
• Bridge is a more Intelligent from of Hub
• Packets are processed based on MAC address
(Hardware Address) inside the incoming packet.
• Swtich = Bridge with more than 2 Ports
• More scalable and Practical
• Bridge is not very useful for end-computig devices
• Hubs cannot handle large data traffic

ROUTERS
 Router is a device which is use to create an
internetworking in our WANs and LANs.
 The main purpose of router is routing, which means
taking a packet from one device and sending it through
the network to another device on a different network.
 A Packet is nothing but the unit of data.
 A packet normally contains Data
Type, Packet Count, Recipient’s IP
address, Sender’s IP address, and
Data.
 Actually routers need to transfer the
data from source machine to
destination machine but other
information in packets it need during
its transportation process.

NETWORK DEVICE DOMAINS

FULLY CONNECTED NETWORKS
 If every subscriber is to be connected to every
other subscriber, then we need a very large
number of links. Every subscriber is directly
connected to every other subscriber. Networks
with this kind of connectivity are called fully
connected networks.
Source: O’Reilly

SWITCHED NETWORKS
 The number of communication links can be
reduced significantly by using a switch along
with communication links for establishing
connection between subscribers.
 Switch, as you know, is a device that is used to
make and break electrical connections.
Switched
communication
networks are those in
which data
transferred from
source to destination
is routed between
various
intermediate nodes

BASICS OF NETWORK TECHNOLOGY
A Network Is Two
Or More Devices
Connected
Together
Through links. A
network link is
communicating
pathway to
transfer data from
one device to
another.
One way to
categorize the
different types
of computer
Network Designs
is by their scope or
scale.
For historical
reasons, the
networking
industry refers to
nearly every type
of design as some
Kind Of Area
Network.

NETWORKING BASICS
 Networks are not new to us. We are familiar with
postal networks, railway networks, airline networks,
etc
 A fundamental difference between telecommunication
and other networks is that telecommunication
networks operate in the electrical, optical or
electromagnetic domains.
 A Computer network includes the network operating
system in the client and server machines, the cables,
which connect different computers and all supporting
hardware in between such as bridges, routers and
switches.
 In wireless systems, antennas and towers are also
part of the network.

ADVANTAGES OF NETWORKS
 Computers in a networked environment provide
numerous advantages when compared to
computers in a stand-alone environment.
Sharing Reliability Scalability
Communication
Medium
Increased
Productivity

NETWORK CLASSIFICATION
 We see different types of networks available like
mobile networks, computer networks and TV
networks around us
 Let us now learn about different types of
computer networks available around us and try
to classify them.
Size
•LAN
•MAN
•WAN
•PAN
Connection
Type
•Wired
Network
•Wireless
Network
Architecture
•Peer to Peer
network
•Client-
Server
Network

NETWORK CLASSIFICATION
• Local Area NetworkLAN
• Wide Area NetworkWAN
• Wireless Local Area NetworkWLAN
• Metropolitan Area NetworkMAN
• Storage Area Network, System Area Network, Server
Area Network, or sometimes Small Area NetworkSAN
• Campus Area Network, Controller Area Network, or
sometimes Cluster Area NetworkCAN
• Personal Area NetworkPAN

LAN (LOCAL AREA NETWORK)
 The network that spans a relatively small area that
is, in the single building or campus is known as
LAN.
 A Library will have a wired or wireless LAN for
users to interconnect local devices (e.g., printers and
servers).
Local area networking
uses switches, bridges
and/or repeaters, and
hubs to interconnect
LANs and increase
overall size.

MAN (METROPOLITAN AREA NETWORK)
 MAN is a Computer network connecting two or more
LANs or CANs (Campus Area Networks) together but within
a Town or City.
 In terms of geographic area MANs are larger than
LANs, but smaller than Wide-Area Networks (WANs).
 MANs are usually characterised by very high-speed
connections using fiber optical cable or other digital
media.
Range is
anywhere from
5 to 50km in
diameter.

WAN (WIDE AREA NETWORK)
 WAN is a computer network that spans a
relatively large geographical area.
 WAN consists of many local-area networks
(LANs)
 They can connect networks Across Cities, States
or even Countries
 They can also be connected through leased lines
or satellites.

PERSONAL AREA NETWORK (PAN)
 A personal area network (PAN) is a computer
network used for communication among
computer devices close to one person.
 Some examples of devices that may be used in a
PAN are printers; fax machines, telephones,
Personal Digital Assistants (PDAs) or Scanners.

TYPE OF CONNECTION
 According to the connection-type, networks can
be classified as using wire connection or wireless
connection:
• A network that connects devices
using cables (wires) like Coaxial
Cable, Twisted pair Cable,
Optical Fiber Cable etc.
Wired
Network
• A network that connects devices
using Wireless technologies like
Bluetooth, Infrared, Radio
Frequency, Wifi etc.
Wireless
Network

FUNCTIONAL RELATIONSHIP
 Functional Relationship or Network architecture could
be another important criteria to classify the networks.
• It is commonly
implemented where less
than ten computers are
involved and where strict
security is not necessary
Peer to
peer
network
• In this architecture each
computer or process on the
network is either a client or
a server. Client/server
networks are more suitable
for larger networks
Client-
Server
Network

LOCAL AREA NETWORK (LAN) TOPOLOGIES
 Topology refers to the shape of a network, or the
network’s layout.
 How different nodes in a network are connected to
each other and how they communicate with each other
is determined by the network’s topology.

BUS TOPOLOGY
• In Bus topology, all devices are connected to a central cable,
called the bus or backbone.
• The bus topology connects workstations using a single cable.
• Each workstation is connected to the next workstation in a
point-to-point fashion.
• All workstations connect to the same cable.

STAR TOPOLOGY
• Star topology uses a central hub through which, all
components are connected.
• In a Star topology, the central hub is the host computer,
and at the end of each connection is a terminal

RING TOPOLOGY
•Ring Topology all devices are connected to one another in
the shape of a closed loop, so that each device is connected
directly to two other devices.
•One on either side of it, i.e., the ring topology connects
workstations in a closed loop.

TREE TOPOLOGY
• Tree topology is a LAN topology in which only one
route exists between any two nodes on the network.
• The pattern of connection resembles a tree in which
all branches spring from one root.

MESH TOPOLOGY
•Devices are connected with many redundant interconnections
between network nodes.
•In a well-connected topology, every node has a connection to
every other node in the network
•The cable requirements are high, but there are redundant
paths built in.
•Failure in one of the computers does not cause the network to
break down

WIRELESS TECHNOLOGY
•As we know wireless transmission means where data
transmission happen without wires.
•No physical connectors between the two communicating
devices.
•In wireless transmission data is sent through the atmosphere
or air.
• Nowadays everyone
wants an
uninterrupted
Omnipresent
network access from
everywhere and
every time.

Wi-Fi is a trademark of the Wi-Fi Alliance for certified
products based on the IEEE 802.11 standards
It is often suggested that Wi-Fi means Wireless Fidelity.
(compared with the long-established audio recording term
High Fidelity or Hi-Fi.)
However, officially the term Wi-Fi does not mean
anything.
WI-FI
Wi-Fi Enabled Devices
• Nowadays we see that most of the personal computer
operating systems, many game consoles, laptops,
smart phones, printers, and other peripherals
support Wi-Fi. Many consumer devices use Wi-Fi.

WIMAX
The meaning of WiMAX is Worldwide Interoperability for Microwave
Access.
“WiMAX” was created by the WiMAX Forum.
Which was formed to promote conformity and interoperability of the
standard.
It is a telecommunications technology that provides wireless
transmission of data using a variety of transmission modes.
From point-to-multipoint links to portable and fully mobile Internet
access.
Less data rate is major problem of wireless technology however through
WiMAX we can reach up to 3 Megabits/second broadband data rate.
IEEE standard available for WiMAX is 802.16 standard

LI-FI
•Li-Fi (Light Fidelity) is wireless communication technology
•Which utilizes light to transmit data and position between devices.
•The term was first introduced by Harald Haas during a 2011 TEDGlobal talk in
Edinburgh
•In technical terms, Li-Fi is a light communication system that is capable of
transmitting data at high speeds over the visible light, ultraviolet, and infrared
spectrums.
•In its present state, only LED lamps can be used for the transmission of visible
light.

WI-FI VS LI- FI

WEB BROWSERS
 Web browsers are used to look for information on the
net while editors are used to create web pages.
 There are many web browsers but the most common
two are Microsoft Internet Explorer and Google
Chrome.

WEB BROWSERS & PAGES
 Editors are used to create web pages
 Pages on the WWW are written primarily in
html (Hypertext Mark-up Language).
 HTML files are plain text files and describe text
formatting and are not a programming language
as such.
 All html documents have the same structure with
different codes, as the designer requires.
 Software that is WYSIWYG – ‘what you see is
what you get’ implies that the contents of the
screen are the same as the final printer or
browser versions.

WORLD WIDE WEB (WWW)
 World Wide Web (WWW) or simply Web is very popular
on the Internet.
 A Large number of business houses, government
agencies and many individuals have their own web
sites.
 The concept of Web started in 1989 in France.
 In 1994, a consortium called World Wide Web
Consortium (W3C) was established.
 W3C now has many countries as its members and is
responsible for development and standards for Web and
its access.
 Web is a collection of documents (Web Pages) scattered
all over the world that are accessible over the Internet.
 These documents are hypertexts as they contain
embedded links to other documents.

UNIFORM RESOURCE LOCATOR (URL)
 Embedded links are in the form of Uniform
Resource Locator (URL) that contains three
parts:
 a resource name, the identification of the
server in which the resource is located and the
protocol that can be used to access the resource

HYPERLINK
 URL is unique identifier for a specific resource on the
Internet anywhere in the world. An embedded URL
is called hyperlink.
 Static web pages are designed using a language
called Hypertext Markup Language (HTML) that
allows a developer to place text, graphics, sound,
video and hyperlinks in a web page.
Web
Pages
Static
Dynamic

HYPERTEXT MARKUP LANGUAGE (HTML)
 HTML defines how documents are to be formatted
and mixes the contents and format information.
 This poses serious problems while editing the pages.
 To overcome this deficiency, two new languages
developed they are,
HTML
XML
XSL
XML sets standards for
structuring the contents XSL for formatting the
pages.

COOKIES
 Cookies are short strings of data that a server
sends along with a web page
 Uses the same later for meeting user
preferences.
 The user, however, has the option of blocking
cookies being stored on his/her system.

HYPERTEXT TRANSFER PROTOCOL
 The protocol used for communication between the
web browser client and the server is called Hypertext
Transfer Protocol (HTTP).
 For secure applications, Secure Hypertext Transfer
Protocol (HTTPS) is used.
 HTTP is used universally to access web services all
over the Internet.
 It specifies how a client may send requests to servers
and how the servers may respond.
 The requests are sent in the form of ASCII (American
Standard Code for Information Interchange) strings and the
responses are received in the form of Multipurpose
Internet Mail Extension (MIME) format.

FILE TRANSFER PROTOCOL (FTP)
 FTP is used to transfer files from one computer to
another on the Internet.
 FTP works in an interactive mode.

SIMPLE MAIL TRANSFER PROTOCOL – (SMTP)
 SMTP (Simple Mail Transfer Protocol)
protocol is used by the Mail Transfer Agent (MTA)
to deliver an email to the recipient’s mail server.
 The SMTP protocol can only be used to send
emails, not to receive them.
 The vast majority of mail servers use SMTP.

NETWORKED ELECTRONIC INFORMATION
SOCIETY (NEIS)
 Networked society means one in which a large
proportion of the world population is
interconnected or networked by some form of
telecommunication system.
 People carry out their day-to-day activities using
the network predominantly.
 Day-to-day activities may involve tasks such as
banking, ticket booking for travel or
entertainment, product ordering, financial
transactions, exchange of mails, retrieving of
information from a database, downloading of
music files, simple telephone conversation etc.

ELECTRONIC TEXT MESSAGING
 Electronic text messaging primarily refers to Small
Messaging Service (SMS).
 SMS offered by mobile communication systems or
Instant Messaging Service (IMS) offered by online
chat rooms on the Internet.
 In the 1990s electronic mail used to be referred to
as text messaging.
 In SMS, the interaction may or may not be in real
time.
 In IMS, it usually happens in real time. Option
here other party even though he/she is not online.

MULTIMEDIA MESSAGING
 Multimedia means a combination of video, sound
and text. Multimedia messaging (MMS) usually
means multimedia information being exchanged
on mobile networks.
 Digital image or still picture is stored and
transmitted using a microscopic process.
 The picture is formed as a matrix of dots called
pixels or pels. The word pixel or pel is a short
form for picture element.
 The horizontal and vertical dot densities together
are called the resolution of the picture.
Tagged Image File Format (TIFF)
Graphics Image Format (GIF)
Joint Picture Expert Group (JPEG)

ELECTRONIC MAIL
 Electronic mail, popularly known as e-mail, is the
most widely used form of communication on the
Internet almost two decades.
 Today it is grown exponentially to the point where
its volume per day is far in excess of the conventional
paper mail
 Fax communication is terminal-to-terminal
 E-mail communication is user-to-user/s
SMTP: Simple Mail Transfer Protocol

INTERACTIVE TELEVISION (ITV)
 Interactive television (ITV) is a network
application for the user.
 Today, television is a broadcast service. Different
channels transmit pre-scheduled programs.
 The user can select a channel of his/her choice
and view the programme that is being telecast
currently.
 ITV offers flexibility and control in viewing
programmes.
 Conventional TV transmission may
be analog or digital whereas ITV is
digital only.
 Conventional TV is available via sky,
satellite or cable communication
whereas ITV is available via network.

VIRTUAL REALITY (VR)
 Virtual reality is a computer-generated
artificial reality that projects a person
into a sensation of three dimensional
space.
 Virtual reality is becoming more popular
in arcade type games.
 Virtual reality is a Simulator.
 A simulator is a device that represents
the behavior of physical or abstract
systems.
 Simulators are used very effectively
in training applications for
aeroplane pilots or bus drivers
to help them deal with various real-
life situations in a safe environment

AUGMENTED REALITY (AR)
 Augmented reality is an interactive experience of
a real-world environment where the objects that
reside in the real world are enhanced by
computer-generated perceptual information.

SECURITY
 In the pre-computer era, information in an
organization used to be secured physical and
administrative measures.
 For example, a conventional library has manual
checks at the entry/exit point.
 In other office areas, secure cabinets and
restricted physical access were used for
information security.
 The electronic information security measures fall
under two different classes:
Information
Security
Network
Security
Computer
Security

SECURITY
Computer
Security
• The measures used for securing information stored
side a computer fall under the class computer
security.
Network
Security
• The measures used while transmitting information
over a network fall under the class network
security.
Information
Security
• Information security, sometimes shortened to
infosec, is the practice of protecting information by
mitigating information risks. It is part of
information risk management.

INFORMATION SECURITY
 Threat to information resources may come from
within an organization or from external sources.
Internal
Threats
External
Threats
WHY INFORMATION SECURITY?
 Information is a valuable commodity and some
persons attempt to derive benefits by exploiting
others’ information resources.
 Attempts may also be made to destroy other’s
information resources to cause harm to the
owner.

AAA SECURITY
 AAA security is predominantly concerned with
access to information resources residing on a
server connected to a network or on a standalone
computer.
 The access may come from a user or a computer
program running on another computer or server.
Authentication
Authorisation
Auditing

FIREWALLS
 Firewall is a device that is designed to protect an
organization's local network from external
attacks while permitting the local network users
to safely access the external resources.
 It is a wall that prevents electronic fires (external
security attacks) from spreading to the local
network
 It acts as a gatekeeper for the local network.
 No one can enter, (i.e., no access can be made to)
the local network without the permission of the
gatekeeper.

PROXY SERVERS
 Proxy servers are computer systems that perform
firewall functions at the application level. In the
sessions layer or applications layer level.
 Hence, proxy servers are also called as
application level firewall.
 Both firewalls and a proxy servers act as single
entry/exit point where security checks and audit
inspections are imposed

DATA SECURITY
 Data security means protecting digital data, such as
those in a database, from destructive forces and from
the unwanted actions of unauthorized users, such as
a cyberattack or a data breach.

MALICIOUS SOFTWARE
 A malicious computer program is one that harms
the normal functioning of a computer.
 Malicious computer programs enter the computer
systems via Internet, and removable mass
storage devices such as floppies, pen drives and
CDs.

ANTIVIRUS
 Anti-Virus programs that keep a continuous watch on what
enters the system.
 Anti-virus programs scan all incoming code and data to ensure
virus-free import.
 They also scan every removable storage device whenever they are
mounted on the system.
 If Viruses are found means it will neutralized or healed. If this is
not possible, the import process is rejected.
 The user is given an appropriate message when scanning is done.
 Antivirus programs usually go through three phases of operation.
Detection Identification Removal

ENCRYPTION
 Encryption is the art of hiding the meaning contained
in a message.
 Decryption is the reverse process of encryption to
extract the hidden meaning.
 The general field of study of encryption and decryption
and related aspects is known as cryptography.
 Cryptography is an age-old technique for
communicating secretly between two parties.
 Military personnel and persons in love have been using
this technique for ages.

SEARCH ENGINES
Internet offers a powerful tool known as search engine to
manage, filter and retrieve the information for their users.
Search engine is a tool for locating information from a
collection.
Search engines uses information about the information (such
as metadata, catalogue) stored in the database to locate
information.
Sometimes they perform full text search within the
document from first character to last character.
The search is done on pattern matching algorithm whether it
is a database or full text.

SEARCH TOOLS
•Academic and Professional Directories
•These are often created and maintained by subject
experts to support the needs of researchers.
•INFOMINE, from the University of California, is a
good example of an academic directory.
•Commercial Directories
•These cater to the needs of general public.
Directories of Yahoo! and Google are examples of
commercial directories.
Search
Directory
•Meta Search engines are online tools (search engines)
which performs simultaneous search on more than
one search engine at a time.
•These search engines aggregates the results into a
single list and displays them according to their
source.
•e.g. Dogpile is a metasearch engine and gets its
results from Google, Yahoo, MSN Search, Ask ,
About, MIVA, LookSmart, and more.
Meta-
search
Engines

FEATURES OF SEARCH TOOLS
Keyword
Search
Boolean
Search
Proximity
Search
Truncation
Search
Case
Sensitive
Search
Limiting
Search
Fields
Search
File
Types
Search
Stop
Words
Ranking
Family
Filters
Fuzzy
Search

INTRUSION DETECTION SYSTEM
• An Intrusion Detection System (IDS) is a system
that monitors network traffic for suspicious activity
and issues alerts when such activity is discovered.
• It is a software application that scans a network or
a system for harmful activity or policy breaching.

IDS AND IPS

UGC NET - Unit 7 (INFORMATION TECHNOLOGY)

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