Tài liệu Module 1: Internet Concepts pdf

Contents Overview 1 Services Available on the Internet 24 Web Development Technologies 31 Lab 1: Working on the Internet 36 Review 38 Module 1: Internet Concepts... It explains the

Contents

Overview 1

Services Available on the Internet 24

Web Development Technologies 31

Lab 1: Working on the Internet 36

Review 38

Module 1: Internet Concepts

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Program Manager: Steve Merrill

Development Lead: Basabjit Chakrabarty (NIIT)

Instructional Designers: Sangeeta Nair, Vijayalakshmi Narayanaswamy (NIIT); Veena Nambier,

Yatinder Walia (NIIT)

Technical Contributors: Scott Swigart (3 Leaf Solutions); Gary Gumbiner (Great Barrier

Technologies, Inc.)

Graphic Artist: Scott Serna (Creative Assets)

Editing Manager: Jennifer Linn

Editor: Reid Bannecker

Production Manager: Miracle Davis

Production Coordinator: Linda Lu Cannon (The Write Stuff)

Build Coordinator: Eric Wagoner

Testing Lead: Eric Meyers

Testing: Bryan Urakawa, Chris and Edward

Lead Product Manager, Internet Services: Hilary Vandal

Manufacturing Manager: Rick Terek

Operations Coordinator: John Williams

Manufacturing Support: Laura King; Kathy Hershey

Lead Product Manager, Release Management: Bo Galford

Group Manager, Courseware Infrastructure: David Bramble

General Manager: Robert Stewart

Instructor Notes

This module provides students with an overview of the Internet It explains the history and the architecture of the Internet, as well as the various types of connections and the services available on the Internet Finally, the module

introduces students to the various Web development tools

After completing this module, students will be able to:

! Describe the architecture of the Internet

! Connect to the Internet

! Identify the services available on the Internet

! Identify the various Web development tools

Materials and Preparation

This section provides you with the materials and preparation needed to teach this module

Required Materials

To teach this module, you need the following materials:

! Microsoft PowerPoint file 1912A_01.ppt

! Module 1, “Internet Concepts”

! Lab 1, “Working on the Internet”

Preparation Tasks

To prepare for this module, you should:

! Read all of the materials for this module

! Complete the labs

Presentation:

60 Minutes

Lab:

10 Minutes

Module Strategy

Use the following strategy to present this module:

! Introduction to the Internet This topic provides an overview of the Internet First, explain the need for a global network Then, introduce the services available on the Internet Finally, explain about intranets and extranets

! Architecture of the Internet This topic explains the architecture and working of the Internet First, explain the need for protocols Then, explain the need for addresses and the various types of addresses Finally, describe the client/server architecture of the Internet

! Connecting to the Internet This topic describes how a client computer connects to a Web server First, describe online services Then, explain what Internet service providers are Finally, describe the various types of Internet connections possible

Highlight the differences between each of the connection types Spend more time on DSL, a new technology

! Services Available on the Internet This topic describes the services available on the Internet Explain each service and its purpose

! Web Development Tools and Technologies This topic covers various Web development tools First, explain markup languages Then, describe scripting languages Finally, explain the COM technologies

# Overview

After completing this module, you will be able to:

! Describe the architecture of the Internet

! Identify various ways to connect to the Internet

! Identify the services available on the Internet

! Identify the various Web development tools

In this module, you will learn

about the Internet, the

services available on the

Internet, the architecture of

the Internet, and how to

connect to the Internet You

will also learn about

electronic commerce and

the Web development tools

and technologies

# Introduction to the Internet

The Internet was created about 30 years ago with the simple objective of allowing disparate computers to communicate with each other Today, the Internet has grown into a vast resource for information and communication It is the single largest network of computers with a host of available services Other types of networks include intranets and extranets An intranet utilizes the same protocols as the Internet and provides many of the same services, such as e-mail and Web pages However, an intranet is for use within an organization and access to the information on an intranet is restricted to the employees of a given organization An extranet is like an intranet except that it allows limited access to users outside the intranet

Slide Objective

To provide an overview of

the Internet

Lead-in

In this section, you will learn

about the history of the

Internet You will also learn

about the various services

available on the Internet

What Is the Internet?

$ A global network of computers

$ Allows one node to communicate with any other node through various paths

$ Currently consists of many small and large networks of computers

$ A vast resource of information

$ Provides popular services, such as the WWW, e- mail, chat rooms, and news

$ ARPAnet, NSFnet

The Internet is a global network of linked computers When you connect to the Internet, your machine is simply another node on this global network The topology of the Internet is like a web, allowing any node to communicate with any other node through various paths

The history of the Internet goes back to 1969 when the Advanced Research Projects Agency (ARPA) of the U.S government started a project to link computers The main objective of this network of computers was to enable research scientists at the Department of Defense to communicate with each other The network was named ARPAnet

The participation of educational institutions—including Harvard University, the University of California, Massachusetts Institute of Technology, and Stanford University—ensured the addition of more computers and the growth of ARPAnet Over a period of time, the size of the network increased and more organizations started adding their own networks to ARPAnet

By 1980, the traffic on ARPAnet had increased tremendously As a result, the National Science Foundation created a nationwide network called the NSFnet Consequently, ARPAnet was withdrawn from the service

The purpose of NSFnet was to provide high-quality computing services to the public across the country NSFnet became the launch pad for the Internet The Internet currently consists of more than 1,300,000 small and large networks

of computers and continues to grow at a rapid rate With more than 50 million Web pages containing an average of 500 words per page, the Internet is the single largest pool of information

The Internet has become a vast resource of information It provides services catering to sports, entertainment, education, news, and current affairs and various other categories The most popular services on the Internet are the World Wide Web, electronic mail, chat rooms, and newsgroups

Slide Objective

To explain the need and

evolution of the Internet

Lead-in

The Internet is an expansive

network of computers and a

cost-effective mode of

communication between two

places across the globe

Services Available on the Internet

WWW

WWW is an abbreviation for World Wide Web, which is often simply referred

to as the Web Many people confuse the Internet with the Web The Web is a subset of the Internet The underlying protocol for the Web is Hypertext Transfer Protocol (HTTP)

E-Mail

E-mail is an electronic messaging service available on the Internet E-mail has brought a radical change in communications across the globe Whenever you send a piece of e-mail, your computer's e-mail software, or e-mail client, interacts with the Simple Mail Transfer Protocol (SMTP) server to send the e-mail message

Slide Objective

To highlight the popular

services available on the

Internet

Lead-in

The Internet is growing at a

phenomenal rate This is

because the Internet

provides information to a

worldwide audience In

addition, the Internet obtains

information with no barriers

in space or time

Intranets

$ Is a smaller version of the Internet

$ Provide information that is of use to the employees of a company

$ Are suitable for high bandwidth services, such as video conferencing

$ Can also contain sensitive and proprietary information

$ The client forwards the request to the server

$ The server processes the request and sends the requested data to the client

An intranet is an internal version of the Internet Intranets typically provide information that is of use to the employees of a company, such as online forms and vacation policies Information about benefits, a forum to share ideas on various projects, and resource scheduling are just a few examples of ways to use an intranet Because the nodes of an intranet typically have higher speed connections, intranets are suitable for high-bandwidth services, such as video conferencing Because they are accessible only to authorized users, intranets

can also contain sensitive and proprietary information

Working of Intranets

Intranets use the client/server architecture and are based on the Internet protocols The client forwards the request to the server The server processes the request and sends the requested data to the client Security measures such as firewalls are required to block access from unauthorized sources

A firewall allows people on an internal network to access the Internet, but prevents people on the Internet from accessing the internal information

Slide Objective

To provide an overview of

intranets

Lead-in

Intranets are private

networks within companies

Extranets

$ Exchange data with other companies

$ Share information with vendors and suppliers

$ Access services provided by other companies

$ Share news of common interest with partner companies

$ Coordinate with other companies on joint ventures

An extranet allows you to:

! Exchange data with other companies

! Share information and news with vendors and suppliers

! Access services provided by other companies

! Share news of common interest with partner companies

! Coordinate with other companies on joint ventures

! Web server security Web server security uses username and password authentication To log on

to an extranet, the user needs to enter the username and password

Slide Objective

To provide an overview of

extranets

Lead-in

Extranets are similar to

intranets; however they can

be accessed by authorized

people outside the

company

! Certification authority Certification authority uses a digital certificate The access is provided to users based on their certificate The certificate is an evidence of their digital identity

# Architecture of the Internet

site, your computer does not know which path on the Internet will connect your computer to the Microsoft site Instead, your computer knows which is its closest gateway and forwards the request to it This gateway might not be able

to connect your computer to the Microsoft site, but it can forward the request to another gateway that does Gateways are network points that perform the function of an entrance to another network Gateways involve the use of routers A router determines the next network point to which a packet, or block

of data, should be forwarded towards its destination A router is connected to two networks and selects a route to send information The choice is based on its current understanding of the state of the networks to which it is connected If your machine is unable to connect to the Internet, the problem may be that it does not know a gateway to which it can send the request

Slide Objective

To describe the architecture

of the Internet

Lead-in

In this section, you will learn

about the architecture of the

Internet You will also learn

about intranets and

extranets

Protocols

$ Protocol used for all communication on the Internet

$ Is a two-layered program, TCP and IP

$ Set of rules for exchanging files, such as text, graphics, still images, sound, and moving images

$ Used to exchange files between computers on the Internet

$ Can be used to download or upload files

$ Also runs on top of TCP/IP

A protocol is a set of communication rules It is a set of standards that ensures various network programs work together Protocols exist at several levels in a telecommunication connection

There are three Internet protocols:

Hypertext Transfer Protocol (HTTP)

HTTP is a set of rules for exchanging files, such as text, graphics, still images, sound, and moving images, on the Web HTTP is a protocol that rides on top of TCP/IP The Web browser is an HTTP client that sends requests to the server When the user enters a URL or clicks a hyperlink, the browser builds an HTTP request The browser sends the request to the IP address indicated by the URL The destination server receives the request and the requested file is returned to the browser after it is processed

FTP

FTP is used to exchange files between computers on the Internet FTP can be used to download or upload files FTP also runs on top of TCP/IP

$ The first section corresponds to a protocol

$ The second section corresponds to an IP address

However, when you browse the Web, you do not enter server addresses

Generally, you use something much more intuitive and easy to remember, such

as www.microsoft.com When you type www.microsoft.com in the Address

text box of your browser window, your browser contacts a Domain Name Server (DNS) The purpose of a DNS is to map the human-readable domain names to IP addresses Once your browser has obtained the address, it uses this number to contact the machine A DNS can be compared to a telephone book For example, when you want to call John Smith, you first have to look John Smith up in the phone book Once you have obtained the phone number for John Smith, you can place the call All the computers on the Internet are divided into two categories based on either an organization type or a geographic location

Slide Objective

To list the addressing

schemes available on the

Internet

Lead-in

With millions of computers

connected to the Internet,

each computer needs a

unique address so that other

computers can locate the

correct information

Organizational domains describe the type or purpose of the organization The following table describes some of the common domain names

Domain Description

COM Commercial organizations EDU Educational institutions GOV Government agencies MIL Military organizations NET Major network support centers

Organizational domains are continually changing, and there are likely to be many more domain names types in the future

Geographic domains are two-letter codes, such as US for the United States, and

CA for Canada The following table lists some country codes

! www.microsoft.com

! 207.68.156.49

The person who registers the domain name is responsible for choosing the appropriate organizational category and the classification system Most domains in the United States use the organizational naming method Domains

in other countries use the geographic method The Internet Network Information Center (InterNIC), under contract to Network Solutions, handles the registration of domain names

! Obtain a domain name for an organization

1 Obtain an IP address from an Internet Service Provider The IP address will come from a block of addresses that are allocated to the provider

2 Submit this IP address, as well as the domain name you want, and the technical and billing information to InterNIC

If the domain name is available, InterNIC assigns it to the user

Note

Delivery Tip

Describe the procedure for

obtaining a domain name for

an organization

After a domain name is assigned, users can move their Web pages from host to host by notifying InterNIC Within a few days of notification, DNS servers all over the world are updated to reflect the new IP address assigned to the domain name

An individual or a small company may only need one IP address However, large companies need blocks of IP addresses and established subdomains For example, microsoft.com is a domain name, and home.microsoft.com is a subdomain of the main Microsoft domain

Resource Addresses

The Web has become a popular place for storing and displaying all manner of information that can be accessed by individuals all over the world The standard Web address is called a Uniform Resource Locator (URL)

Here is an example of a URL:

http://www.msn.com/tutorial/default.html The first section of a URL corresponds to the protocol of the service you are using, such as HTTP or FTP The second section of a URL corresponds to a DNS address that is translated into a numeric IP address when a request is sent

In the example above, the subdomain name www appears immediately before the logical domain name, msn.com, in the URL The owner of the domain can change the subdomain name The subdomain name reflects the domain server that is dedicated for a service For example, www.microsoft.com,

moli.microsoft.com, and ftp.microsoft.com are within the domain of microsoft.com, but are on different subdomain servers

The information to the right of the domain name in the address http://www.msn.com/tutorial/default.html is the path on the server for that particular file This path is similar to the path for a file on a personal computer

If the path is omitted, the server provides a default response based on the protocol used For example, the default response to an HTTP request is to send the file named Index.htm or Default.htm Usually, you can specify the default response in the server setup

Some URLs are case-sensitive The first section of the URL http://www.company.com is not case-sensitive, but the path and the file name information may be case-sensitive on some operating systems, such as UNIX If

a URL does not work, verify that you typed it in the same case as it was provided

E-Mail Addresses

Once you understand the concept of domain names, understanding an e-mail address is relatively easy The organizations that have a LAN and use internal e-mail create e-mail names based on a naming convention For example, you use your first name and last initial, or firstname_lastname The address must be unique within the organization

Note

If your organization connects the LAN to the Internet, the organization registers

a domain name such as MyCompany.com Then, your Internet e-mail address is your organization e-mail address combined with the domain name of your organization, such as:

someone@mycompany.com

If your Internet access is provided through an Internet service provider (ISP) or

an online service, the domain name in the e-mail address is the domain of the ISP or online service

There are numerous online search and directory services to help you find e-mail addresses

If you choose to integrate Internet Explorer 5.0 with your desktop, the

Find People command is added to the Find submenu on the Start menu You

use this command to search directory services for an e-mail address or a physical address or phone number

To search for an e-mail address, go to any of the following sites:

case-Note

Note

Practice: Obtaining IP Addresses

In this exercise, you will use the ping and ipconfig utilities to obtain IP addresses

! Use the ping utility

1 On the Start menu, point to Programs, then point to Accessories, and then click Command Prompt

2 At the command prompt, type ping <machine name> and press ENTER

Notice the IP address of the machine

! Use the ipconfig utility

1 Open the Command Prompt

2 Run ipconfig with the parameter all Type ipconfig/all, and then press

Slide Objective

To introduce the practice

Lead-in

In this practice, you will

obtain the IP address of a

server

Delivery Tip

For this exercise, provide

students with a computer

name that they can ping

Client/Server Architecture

Computers linked to the Internet are categorized as servers or clients A server

is a computer that provides services to clients To view a Web page, a client specifies the URL of the files in the address bar of the browser window After the URL is specified, the following steps are carried out:

1 The browser breaks the URL into the following three parts:

3 The browser forms a connection with the specified IP address

4 The browser sends a protocol-specific request to the server for the specified file

5 The server returns the file to the browser

6 The browser interprets the HTML tags, formats the file, and displays the file

in the browser window

followed to display the

requested page in your

browser window

# Connecting to the Internet

You can also connect to the Internet through an Internet Service Provider (ISP)

An ISP provides fewer services than an online service and little additional content of its own ISPs are generally less expensive and impose fewer restrictions than online services For example, instead of using a proprietary client, you can use any Web browser of your choice ISPs also tend to support new methods of connection, such as DSL and ISDN, sooner than online services

You can use a dial-up connection, ISDN lines, DSL, or cable modems to connect to the Internet

Depending on your requirements, the type of Internet connection you use may vary For example, you might need to connect to the Internet from your home computer, in which case you would require a relatively simple and inexpensive connection that is suitable for just one user at a time The situation would be different in an organization in which 20 people need to connect to the Internet

at the same time

Slide Objective

To list the ways that you can

connect to the Internet

Lead-in

Online services and ISPs

are companies that provide

Internet connection and

related services