What is the Internet? Describe its brief history

THE INTERNET 

The Internet is a network of a large number of computer networks around the world. It is a data communication system. Through this system millions of computers have been linked together. The Internet consists of both the hardware and the software. The hardware comprises the computer and the connections between them. The software consists of programs that let these computers communicate with each other. More than 65,000 computer networks and 20 million computers are permanently attached to the Internet. Connections to the Internet are available in about 150 countries and 50 million people have access to it. All three major media of communication are use to connect the networks and the computers in the Internet.

(1) Telephone Lines

(2) Fiber-optic cables

(3) Satellite communications

   

There are generally three types of computers in the Internet. These are hosts servers and users.

• Hosts store information in the form of text pictures sound and video films.

• Servers allow users to connect to the Internet. Servers also help the to store and share information on the Internet.

• Users use information stored on the hosts and pass messages to gather computers attached to the Internet.

Who Developed the Internet?

The Government of the United States started a project in 1960s to develop an efficient system of data communication. Under this project a network of 4 computers was established in September 1969 in the United States. The idea of computer networking soon became popular. Several universities and research organizations developed their own computer networks. They joined their networks to the US Government network. The original communication network became a network of networks. This network of computer networks was called the Internet.

Who Owns the Internet?

There is no single organization or government who control the available on the Internet. Millions of people now have access to the Internet. They use it to get information play game and communication also use the Internet to advertise and sell goods.

How to connect to the Internet?

The Internet can be accessed by connecting a personal computer to the Server of an Internet Service Provider (ISP) through telephone lines. To link up an ISP following is required:

A computer

Any computer can be used but it is easier to use a computer running under Windows Operating System.

A modem

It is an electronic device that links a user computer to the Server of the ISP via telephone lines.

Dial Up Software

Dial Up Networking software establishes connection between the personal computer and the Server of the ISP. This software is built into the Windows Operating System.

Web Browser 

A browser is required for browsing or surfing the Internet.

Membership of an ISP

Membership of an ISP permits a member to connect to its Server.

What is the World Wide Web?

THE WORLD WIDE WEB

The millions of linked documents stored on compute permanently connected to the Internet throughout the world are called the World Wide Web. It is abbreviated as www or 3w. The documents on the Web contain information in the form of texts graphics videos clips and sounds. These documents are also called Web page and are stored on computers permanently connected to the Internet. The computers containing these documents are called Web sites or sites. Each web site has a unique name called site address. Site addresses are also called domain name or URL (Universal Resource Locator). A domain name or URL is made up of two or more names separated by dots.

HOW TO CREATE A WEB PAGE

Web pages are written in hypertext. Hypertext provides several facilities that are not available in conventional text documents. A hypertext document can:

1. Show text in different founts and colors.

2. Have sounds video clips and animations.

3. Provide links to other documents on the web.

The links to other documents or pages are called hyperlinks. Hyperlinks in web pages connect all pages available on the web and make it the World Wide Web. The user can directly go to the linked page just by clicking on the hyperlink. Hypertext documents are prepared using special languages. The most popular hypertext languages include XMGL, WML and WAP.

HOW TO LOCATE A PAGE

Each web is stored on a computer permanently connected to the Internet in a file. Each file is given a unique address. It is called Universal Resource Locator or URL. URL is sometime pronounced as earl. It has particular format. http://  The URL begins with the protocol. http stands for Hypertext Transfer Protocol.

SMTP Services

The SMTP Service processes incoming traffic from any SMTP host. SMTP is also used in most communications between Exchange Servers (except Exchange 5.x Servers which use RPC for message transferring). SMTP is also responsible for some advanced Exchange Server functions like Message Journaling. During the Exchange installation, the built in SMTP Service from Windows Server 2003 will be extended with several new functions. Some of the Enhancements are:

• Moving the Message Queue Directories to the Exchange installation Directory
• Providing support for the LSA (Link State Algorithm) in SMTP
• Moving SMTP Messaging from IIS to the Exchange System Manager

Message Flow

• MAPI client sends a message to a remote recipient
• Information Store (Store.exe) receives the message
• The created MailMsg object is forwarded to the Advanced Queue Engine (AQE)
• The Message Categorizer from the AQE processes the MailMsg object and splits it into MIME or RTF as necessary
• The Message Categorizer expands groups and checks defined Message limits on Exchange
• The MailMsg object is then transferred to the Remote Destination Domain within the AQE
• The AQE passes the destination address to the Exchange Routing Engine
• The AQE passes the destination address to the Exchange Routing Engine
• SMTP initiates an SMTP session with the remote SMTP host
• After the SMTP session with the remote host has been established, the information store retrieves the body of the message and converts the message as necessary
• SMTP sends the Message from the Queue to the Remote Host

The following Exchange Features require the use of SMTP:

• Intra Server Message Delivery
• Inter Server Message Delivery
• Message Delivery to the Internet
• Exchange of Routing Information

Diagnostic Logging

One other troubleshooting helper is the Diagnostic Logging of Exchange Server 2003. Diagnostic Logging sets the details that are logged in the Event Viewer for specific Exchange components to a higher level, so more information will be logged in the Event Viewer Application Log .

Diagnostic Logging should only be enabled when troubleshooting specific problems because Diagnostic Logging quickly fills the Event Log. The Logging Level can be set from None to Maximum in the GUI but there is also a Registry Key for setting the Logging Level to Level 7 for SMTP Logging purposes.

Diagnostic Logging must be enabled in the Exchange System Manager under the Exchange Server object.

After enabling the Diagnostic Logging feature the Event Viewer can be analyzed for specific problems.