CONCEPT OF
NETWORKING
Exchange of information is required in many situations between two
users. In such situations, data communications is very much required. Data
communication refers to the transmission of data from one computer to another
by a data carrier cable that connects two computers.
Computer Network can be defined as an interconnected of autonomous
(independent) computers. Normally, these computers are connected through a
copper wire. Computer network connection can be of two types.
There are two important computers in a network i.e., Server
Computer and Client Computer. Server Computer is the main computer that stores
the data of all the clients, shares the files and peripherals with the clients.
Client Computer is a subordinate computer connected to the Server Computer. It
can access the files and peripherals of Server Computer. There can be more than
one client computers.
THE USES OF
A NETWORK
The computer networks offer many uses to its users. While computer
networks provide data sharing, device sharing, flexibility and high reliability
in data communication, they do offer very specific benefits to the network
users. They are :
1
Simultaneous Access :
Because of networked environment, all users in a company can
access the same data at the same time. A central server or simply server
maintains the commonly used data which can be shared among several people. If
one user modifies the shared data, other users in the network will see the
modification when they access it.
2 Shared
Peripheral devices :
It is very difficult to provide every user one PC and one printer
in a company. Because of the networking of PCs, a single printer can be made as
a shared device. All users in that network can share this printer to print
their jobs. This reduces the cost and space required to purchase and install
several printers.
3 Personal
Communication :
Because of computer networks and the Internet which is a network
of networks, it is possible for us to have personal communications with any
person in the world. The common form of personal communication is achieved
through an electronic mail. However, due to many protocols and electronic
equipment, we can have teleconference with the remote user. Video conferencing and
audio conferencing have made the world very small.
4 Easier to
backup :
Data in any business is extremely critical. One should take the
back up of such data. Network provides a shared storage device on which the
backups of critical data is stored and accessed as and when required.
COMMON TYPES
OF NETWORKS
1 LOCAL AREA
NETWORKS [LAN]
This is an interconnection of autonomous computers within a single
building or a small campus. The range of LANs may vary from 10m to 1.5 km. LANs
are small sized networks. In LAN
transmission technology, each computer usually contains a network interface
device that connects the computer directly to the network medium such as a
copper wire or coaxial cable. LANs operate between 10 Mbps and 2 Gbps. Since
LAN technology covers short distances, they offer lower delays and make very
few errors.
2 WIDE AREA
NETWORKS [WAN]
This is a collection of computers that are geographically spread
over a wide area. There is no limitation on the distance it spans. A WAN can
span over a country or a continent. WANs operate usually at slower speeds.
Typical speeds for a WAN range from 2 Mbps to 625 Mbps. They offer a much
greater delay between connections. It is due to far distances. This delay is
due to sending signals to a satellite orbiting the earth.
3
METROPOLITAN AREA NETWORK [MAN]
This is a larger computer network as compared to LANs. It connects multiple corporate LANs
together. It is generally called
MAN. You might have heard people saying “There is a MAN between a LAN and WAN”.
The MANs are high-speed networks for sharing the regional information and resources.
DIFFERRENT
BETWEEN LAN AND WAN :
|
LAN |
WAN |
|
|
1 |
Diameter
of not more than a few kilometer |
Span
entire countries |
|
2 |
A total
rate of at least several mbps |
Data rate less
than 1 mbps to 10 mpbs |
|
3 |
Complete
ownership by single organization |
Owned by
multiple organization |
|
4 |
Very low
error rates |
Comparatively
higher error rates |
INTERNET
Internet is a network of many computer networks. It connects LANs,
WANs and even our own personal computer. It is also called the Information
Super Highway. We can access any information from any place at anytime on the
Internet. We can download to our PC the research papers, send mails to the
friends and relatives, watch a movie, deposit or withdraw money online and sell
or buy products and services.
·
The internet
is often referred to as the “Information Super
Highway”
·
No one owns
the Internet, but everyone connected to it owns part of it.
·
It is not
governed by any central authority but there are agencies and societies that
perform coordinating functions, such as the registration of domain names.
·
In 1988,
there were about 1 million people with access to the Internet. Currently, there
are more than 500 million Internet connections, divided across almost every
country in the world.
·
The web
sites produced by institutions, business and private users cover just about
every imaginable topic.
·
The Internet
was developed in 1969 as a communications network for the US military. Soon,
other government agencies, colleges and research companies began using the Internet.
·
Internet
telephony is a relatively new technology used to digitize sound and transfer it
across the Internet.
·
Video
conferencing technology for the World Wide Web had been developed.
In order to avail the facilities of internet, our PCs must be
connected to the Internet. Therefore, we have to become the subscriber to the
Internet. There are many Internet service providers around the globe. In India,
BSNL (Bharatiya Sanchar Nigama Ltd) provides Internet Services. Presently, some
private organizations like Satyam Infoway, BPL, Wipro etc., started providing
Internet Services. These organizations are called ISPs (Internet Service
Providers).
CONNECTING
TO THE INTERNET :
To connect
your PC to the Internet, the following hardware and software are required.
1.
Modem : It stands for Modulator to Demodulator. It is used to connect the PC to a
telephone line.
2.
Telephone
Line : To transmit data or message over a wide
area.
3.
A PPP (point
to point protocol) account with an Internet service provider.
4.
Internet
connection software (TCP/IP)
5.
Software for
E-mailing, browsing the web and so on. (Internet Explorer)
SERVICES OF
INTERNET
1 Net
Banking
Net Banking as replaced the conventional way of banking. Net
Banking help us in depositing, withdraw or updating the account with just a
click on mouse. We can also get the required information about our Bank Account.
2 Education
No more requires the student has to go college, register and attend
the class. Infact a student can now not only register and attend the classes
but also give exams for that particular class using Internet.
3 Employment
This system with which job sector can register and obtain
information for the vacancies with the various companies.
4 Seminar,
Discussion :
Participating in a discussion about your favourite TV Show with
like minded people across the globe. The Internet community is an open form
that no government or restrictions. The citizens of this community are termed
as Netizens.
5 Greetings
:
Sending and receiving greetings for various occasions across the
globe.
6 Searching
for Information :
Internet provides search engine websites. These websites allows to
search the information using keywords. The popular search engines are
www.google.com, ww.khoj.com, www.yahoo.com etc.,
7 Chatting :
If you like to speak or talk and makes new friends. Then Internet
is the best place, with chat program you can talk with a group of people whose
geographical location you don’t know.
8 E-Mails :
With E-Mails we can send and receive mail messages. E-Mails can be
send globally just by paying local telephone charges.
9 Telnet to
Other Computer :
With Telnet program you can connect to another computer and use as
if you are sitting at it’s keyboard.
INTRANET AND
EXTRANETS
Intranet is a scaled-down Internet. It is a corporate specific
Internet. That is, each and every company may have its own private Internet to
serve the needs of its employees and selected contractors who work within the
company. Outsiders cannot access intranet. It connects a set of computers using
a standard Internet Protocols such as TCP/IP and HTTP.
Extranet is also a scaled-down Internet. It is a great facility to
the employees who can access the resources of their company while they are
travelling onsite or working from home. It plays a role of business-to-business
Internet which allows a limited, controlled, secure access between a company’s
intranet and designated, authenticated users located outside the organization.
The employees or business partners who have a valid username and password can
access the selected information.
DEFINITION
OF WEBPAGE
A hypertext document is called a web page. Web pages are just
ordinary computer files with a few tags added to tell your computer how to
display the contents of the file. A webpage is a page within a website. A
website contains few or many of such web pages.
MEANING OF
HTML
HTML stands for Hypertext Markup Language. HTML is a language used
to markup the web contents. That is, it specifies how the contents of the
WebPages are displayed on the browser. It stands for hypertext markup language.
HTML provides a set of tags (or commands) for marking up the web contents.
DEFINITION
OF WEBSITE
It is collection of web pages. We can also say that it is a
computer system that is set up to distribute documents stored in its database.
Websites range in size from as little as one page to a vast number of pages,
such as those of search engine’s database or a full text book. The websites are
hoisted on the web servers.
WEB
ADDRESSES (URL)
URL is an acronym for Uniform Resource Locator. The URL specifies
the Internet address of a file stored on a host computer connected to the
Internet. Every file on the Internet, no matter what its access protocol, has a
unique URL. Web browsers use the URL to retrieve the file from the host
computer and the specific directory in which it resides. This file is
downloaded to the user’s client computer and displayed on the monitor connected
to the machine.
URLs are translated into numeric addresses using the Domain Name
System (DNS). The DNS is a worldwide system of servers that stores location
pointers to websites. The general format of a URL is as follows : type://address/path/filename
|
Where, type |
€ |
type of
server where the file is located |
|
address |
€ |
address of
the server |
|
path |
€ |
location
within the file structure of the server |
|
filename |
€ |
name of
the file which has the required contents |
Example: https://sayadasite.blogspot.com
Domain Names describe organizational or geographical relativities.
It indicates the country where the network connection is in the kind of
organization that owns it etc,
Following
are examples of domain names and their meaning
com – Commercial edu – Educational gov – Government
net – An administrative organization for a network, mil – Non
classified Military Networks,
org – Usually private organization and other
There are
also domain names for countries
dc – Germany ( Dutch land ) it – Italy
nz – New Zealand in – India
WEB BROWSING
TOOLS
A web browser or simply browser is a program designed to find the
hypertext documents on the web. Once it finds the documents it opens that
documents on the computer from which search was made. The browser translates
the web files into text, images, sound, video etc., Some of the popular Web
browsers are :
·
Internet Explorer(Microsoft)
·
Netscape
Navigator
·
Netscape Communicator
·
Lynx
·
Mosaic
·
Hot Java
ISP’S IN INDIA AND THEIR
RESPONSIBILITIES
In order to avail the facilities of internet, our PCs must be
connected to the Internet. Therefore, we have to become the subscriber to the
Internet. There are many Internet service providers around the globe. In India,
BSNL (Bharatiya Sanchar Nigama Ltd) provides Internet Services. Presently, some
private organizations like Satyam Infoway, BPL, Wipro, TATA DOCOMO, Airtel,
Idea etc., started providing Internet Services. These organizations are called
ISPs (Internet Service Providers).
RESPONSIBILITIES
OF ISP’s
1)
Provide a
reliable and accessible conduit for traffic and services.
2)
Provide
authentic and authoritative routing information
3)
Provide
authentic and authoritative naming information
4)
Report
anonymzed security incident statistics to the
public
5)
Educate
customers about threats
6)
Inform
customers of apparent infections in their infrastructure
7)
Warn other
ISPs of imminent danger and help in emergencies
8)
Avoid aiding
and abetting criminal activity.
EMAIL
This is a short form of Electronic Mail. It allows users to compose messages and send them to remote
individuals or groups. It also allows users to read the incoming e-mails. It is
the most widely used Internet service. It offers
a fast and convenient method of transferring messages. Everyone should have a
e-mail address to send & receive e-mails.
An E-mail system consists of two sub systems : the user agents and
message transfer agents. The user agents allow users to send and receive
e-mail. The message transfer agents move the messages from one computer to
another over network.
The E-mail system is no longer restricted to exchange only text
information it is also used to deliver voice mail, facsimiles and audio-visual
images. When you compose an e-mail and send it to the receiver, it will be available
to the receiver within a few seconds. So, e-mailing is one of the fastest ways
of communication. Every e-mail address has the form:
username@organization_name.typeoforganization
Example :reemayono@gmail.com
Advantages
of E-mail :
1)
Low Cost : Email extremely cost-effective way to move information around, the world.
2)
Speed : Electronic mail can be
delivered almost as fast as the wire can carry
it.
3)
Waste reduction : Email goes a long way toward reducing the wastage of paper in
the modern office
4)
Ease of use : It is easy to send an email.
You don’t have to retype it, find on envelope, get a stamp then find mail box
5)
Record maintenance : Because all messages are
digital files, you can automatically
maintain a record of communications
CHATTING
On the Internet, chatting is talking to other people who are using
the Internet at the same time you are. Usually, this "talking" is the
exchange of typed-in messages requiring one site as the repository for the
messages (or "chat site") and a group of users who take part from
anywhere on the Internet. In some cases, a private chat can be arranged between
two parties who meet initially in a group chat. Chats can be ongoing or
scheduled for a particular time and duration. Most chats are focused on a
particular topic of interest and some involve guest experts or famous people
who "talk" to anyone joining the chat. A chat can also be conducted
using sound or sound and video.
VIDEO
CONFERENCING
A videoconference is a live connection between people in separate
locations for the purpose of communication, usually involving audio and often
text as well as video. At its simplest, videoconferencing provides transmission
of static images and text between two locations. At its most sophisticated, it
provides transmission of full-motion video images and high-quality audio
between multiple locations.
A videoconference can be thought of as a phone call with pictures
- Microsoft refers to that aspect of its NetMeeting package as a "web
phone" - and indications suggest that videoconferencing will someday
become the primary mode of distance communication.
SEARCH
ENGINE
This is a program that locates information in its database. A
search engine functions as a service that searches for information on the
Internet. It responds by matching your query terms to the search engine’s index
terms in its database, ranking the matches and returning the hits to you. You
can type your search keyword and submit for searching. Within a few seconds you
will find lots of related pages displayed on the screen. If you do not find the
exact match you can search further and so on till you get what you want. Some
of the popular search engines are listed below.
·
Alta Vista
·
Dogpile
·
Excite
·
Fast
·
Google
·
HotBot
·
Infoseek
UPLOADING
AND DOWNLOADING FILES
·
Look Smart
·
Savvy Search
·
Yahoo
·
Snap
·
WebCrawler
·
Khoj
The process of copying a webpage onto a web server is called
publishing the page. It is also called Uploading Files.
The reverse process of copying a webpage from the web server to
your local disk is called Downloading Files.
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