Network- Types, WWW, Structure of Web, HTML, Domain Name Systems

1. INTERNET
DR. K. RAMESHKUMAR
ASSISTANT PROFESSOR
PG & RESEARCH DEPT. OF ZOOLOGY
Vivekananda College
Tiruvedakam- West
MADURAI - Dt

2. Internet
 The Internet is a worldwide collection of computer
networks
 It is the largest network in the world that connects
thousands of individual networks all over the
world.
 The popular term for the Internet is the
“information highway”.

3.  Rather than moving through geographical space, it
moves your ideas and information through
cyberspace – the space of electronic movement of
ideas and information.
 The Internet is a network of networks that connects
users in every country in the world. There are
currently over one billion Internet users worldwide.

5. The uses of the Internet
 Send e-mail messages.
 Send (upload) or receive (down load) files
between computers.
 Participate in discussion groups, such as
mailing lists and newsgroups.
 Surfing the web.

6. How to access the Internet?
 Many schools and businesses have direct access
to the Internet using special high-speed
communication lines and equipment.
 Students and employees can access through the
organization’s local area networks (LAN) or
through their own personal computers.
 Another way to access the Internet is through
Internet Service Provider (ISP).

7. How to access the Internet?
 To access the Internet, an existing network need to pay
a small registration fee and agree to certain standards
based on the TCP/IP (Transmission Control
Protocol/Internet Protocol) reference model.
 Each organization pays for its own networks and its
own telephone bills, but those costs usually exist
independent of the internet.
 The regional Internet companies route and forward all
traffic and the cost is still only that of a local telephone
call.

8. Network
 Most people work in a network environment
 A network is a collection of computers connected
together with special hardware and software to
manage it.
LAN – Local Area Network (small area)
WAN – Wide Area Network (long distances)

9. From LAN to WAN
(a) Home Network
(b) Local Area Network

10. From LAN to WAN (continued)
(c) Wide Area Network

11. Internet Service Provider (ISP)
 A commercial organization with permanent
connection to the Internet that sells temporary
connections to subscribers.
 Examples: Prodigy, America Online, Microsoft
network, AT&T Networks.

12. The Internet and How We Connect to It
Using an ISP

13. The Internet and How We Connect to It
Using an ISP

14. The Internet and How We Connect to It
Using an ISP
 ISPs provide a variety of ways to connect to the
Internet, depending on location and desired
connection speed.
 The choice of Internet access technologies
depends on availability, cost, access device
used, media used and the speed of the
connection.

16. The Internet and How We Connect to It Using
an ISP
 The contract with the ISP determines the type and level of
services that are available.

17. How Information is Sent When Using an ISP
 The most important protocol of the Internet is the
Internet Protocol (IP).

18. The World Wide Web (www)
 The Web presents information through multimedia formats:
graphics, sound, animation, and video.
 The Web uses several tools to provide a visual layout:
 Hypertext links
 Browser software
 Code structure
 The Web resembles an electronic library – each location or
site is like a book.
 These books are created using Hypertext Markup Language
(HTML).
 These materials, along with interactive objects such as Java,
JavaScript, and VBScript adds functionality to web pages.

19. Structure of the Web
 Web is a collection of files that reside on computers,
called Web servers, that are located all over the world
and are connected to each other through the Internet.
 When you use your Internet connection to become part
of the Web, your computer becomes a Web client in a
worldwide client/server network.
 A Web browser is the software that you run on your
computer to make it work as a web client.

20. Client vs. Server
 When you connect to Internet to become part of
the web, your computer becomes a Web client in
a worldwide client/server network.
 Web browser is the software that you run on
your computer to make it work as a Web client.

21. Hypertext Markup Language
(HTML)
 The public files on the web servers are ordinary text
files, much like the files used by word-processing
software.
 To allow Web browser software to read them, the
text must be formatted according to a generally
accepted standard.
 The standard used on the web is Hypertext markup
language (HTML).

22. Hypertext Markup Language (HTML)
 HTML uses codes, or tags, to tell the Web browser software
how to display the text contained in the document.
 For example, a Web browser reading the following line of text:
<B> A Review of the Book<I>Wind Instruments of the
18th Century</I></B>
 recognizes the <B> and </B> tags as instructions to display
the entire line of text in bold and the <I> and </I> tags as
instructions to display the text enclosed by those tags in italics.

23. Connecting to the Internet
 Elements required to connect to the Internet:
Computer, WebTV, mobile phone, or Personal Digital Assistant (PDA)
Dial-up modem, digital subscriber line (DSL) modem, or cable modem
Operating System: Windows 95/98/Me, Windows NT/2000/XP,
Linux/UNIX, Macintosh
Telecommunications/Client Software: Web browser, e-mail or news client
programs
Internet Connection (telephone line or cable connection): dial-up or direct
connection to an Internet Service Provider (ISP) or Value-Added Network
(VAN) such as America Online (AOL) or Microsoft Network (MSN)
Internet Addresses: Web addresses (e.g., www.msn.com), e-mail addresses
(e.g., student@class.com), server addresses (e.g., ss1.ProSoftTraining)

24. Connecting to the Internet
• At Work or School
– Via a Local Area Network
• At Home
– Traditional Modem (56Kbps)
– Cable Modem
• Uses TV cable
• Requires network card
– DSL Modem
• Voice and data on the same line
• Requires network card

25. Connection Types
 Dial-Up Connection
Use a modem to access the Internet on a per-use basis. The user
accesses the ISP via phone line and when finished, disconnects
from the ISP.
The speed of access is determined by the speed of your modem.
To gain faster access, you can install an Integrated Services Digital
Network (ISDN) line, which is a digital phone line.
 Direct Connection
Provide continuous access to the Internet
Convenient and fast and capable of handling high bandwidth

26. Domain Name System (DNS)
 To access a website, you must enter the address of the
web server in your browser.
 The IP address (the dotted quad) is one way to identify
the server; however, most users prefer to use domain
names because they are easier to remember.
 The Domain Name System (DNS) translates IP
addresses into easily recognizable names.
 Examples: IP address: 72.64.56.86
Domain name: www.microsoft.com

27. Domain Names
Each domain name is unique. It consists of letters
and numbers separated by dots and includes two or
more words (labels).
The last label in a domain name is usually a two- or
three-letter code called a top-level domain.
Example: www.microsoft.com
Server (Host) Name Registered Company Domain Category
Domain Name (Top-Level Domain)

28. Domain Name Syntax
 A domain name, read left to right, specifies general
divisions, then specific companies, and individual
computers (web servers or e-mail servers)
com = a commercial site
microsoft = the name registered by the
company
www = the name of the web server at the
company, also called the web site host

29. Domain Names
 A fully qualified domain name (FQDN) is the complete domain
name of an Internet computer. It provides enough information to
covert the domain name to an IP address.
 Top-Level Domains
.com = commercial or company sites
.edu = educational institutions
.gov = U. S. civilian government
.mil = U. S. military
.org = organizations
.net = network sites, including commercial ISPs
.int = international organizations
 Two-Letter Country Codes – categorize domains by country or
region. For example: us = United States
au = Australia

30. Addresses on the Web: IP Addressing
 Each computer on the internet does have a unique
identification number, called an IP (Internet
Protocol) address.
 The IP addressing system currently in use on the
Internet uses a four-part number.
 Each part of the address is a number ranging from
0 to 255, and each part is separated from the
previous part by period,
 For example, 106.29.242.17

31. IP Addressing
 The combination of the four IP address parts
provides 4.2 billion possible addresses (256 x 256 x
256 x 256).
 This number seemed adequate until 1998.
 Members of various Internet task forces are
working to develop an alternate addressing system
that will accommodate the projected growth.
 However, all of their working solutions require
extensive hardware and software changes
throughout the Internet.

32. Domain Name Addressing
 Most web browsers do not use the IP address t locate Web
sites and individual pages.
 They use domain name addressing.
 A domain name is a unique name associated with a
specific IP address by a program that runs on an Internet
host computer.
 This program, which coordinates the IP addresses and
domain names for all computers attached to it, is called
DNS (Domain Name System ) software.
 The host computer that runs this software is called a
domain name server.

33. Domain Name Addressing
 Domain names can include any number of parts separated by
periods, however most domain names currently in use have only
three or four parts.
 Domain names follow hierarchical model that you can follow
from top to bottom if you read the name from the right to the
left.
 For example, the domain name gsb.uchicago.edu is the
computer connected to the Internet at the Graduate School of
Business (gsb), which is an academic unit of the University of
Chicago (uchicago), which is an educational institution (edu).
 No other computer on the Internet has the same domain name.

34. Uniform Resource Locators
 The IP address and the domain name each identify a particular
computer on the Internet.
 However, they do not indicate where a Web page’s HTML
document resides on that computer.
 To identify a Web pages exact location, Web browsers rely on
Uniform Resource Locator (URL).
 URL is a four-part addressing scheme that tells the Web
browser:
 What transfer protocol to use for transporting the file
 The domain name of the computer on which the file resides
 The pathname of the folder or directory on the computer on
which the file resides
 The name of the file

35. Structure of a Uniform Resource
Locators
http://www.chicagosymphony.org/civicconcerts/index.htm
protocol
Domain name
pathname
filename
http => Hypertext Transfer Protocol

36. HTTP
 The transfer protocol is the set of rules that the
computers use to move files from one computer
to another on the Internet.
 The most common transfer protocol used on the
Internet is the Hypertext Transfer Protocol (HTTP).
 Two other protocols that you can use on the
Internet are the File Transfer Protocol (FTP) and
the Telnet Protocol

37. How to find information on the Web?
 A number of search tools have been developed and
available to you on certain Web sites that provide search
services to help you find information.
 Examples:
 Yahoo  www.yahoo.com
 Excite  www.excite.com
 Lycos  www.lycos.com
 AltaVista  www/alta-vista.com
 MSN WebSearch  www.search.msn.com

38. How to find information on the Web?
 You can find information by two basic means.
 Search by Topic and Search by keywords.
 Some search services offer both methods, others only
one.
 Yahoo offers both.
 Search by Topic
You can navigate through topic lists
 Search by keywords
You can navigate by entering a keyword or phase into a
search text box.