Internet and its Services

WWW & INTERNET!

World Wide Web (WWW) is a system of Internet Servers that support specially formatted documents (called hypertext documents). The documents are formatted in a markup language called HTML that supports links to other documents, as well as graphics, audio and video files. The World Wide Web was created in 1989 by Sir Tim Berners Lee, working at CERN in Geneva, Switzerland.

The WWW, or simply Web provides a way for accessing any information over the medium of Internet. It is an information sharing model that is built on top of the Internet. It allows computer users to locate and view multimedia based documents (i.e., documents containing text, graphics, animation, audio and video) on almost any subjects. It uses HTTP protocol to transmit data over the Internet.

With a Web Browser (client web application), user can view the web pages that contain text, images, videos and other multimedia and navigates between them, using the hyper links. There are several Web Browsers available now days; two of them are Netscape Navigator and Microsoft Internet Explorer.

Internet:

The Internet is a global and grand computer network, called the network of networks. It is a global TCP/IP-based network. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are connected to the Internet.

Through Internet, we can link a large number of autonomous systems, intranets, LANs, MANs and WANs. No organization owns and controls it. But, it operates in the public domain. The information that travels over the Internet does so via a variety of language known as Protocols.

Intranet:

An intranet links a number of autonomous systems of an organization. It differs from the Internet in following ways:

1. Though the protocol and technology used for Intranet is reasonably similar to that of the Internet, the access is not public.
2. The intranet can, by appropriate tools, facilitate audio and video conferencing, file sharing and transfers. It also employs software tools for authentication, access control, secure transmission, disaster recovery and virus protection.

Intranet & WWW:

The Internet refers to the hardware and the media used for forming a Wide Area Network. Communication between two computers connected in the Internet takes place via a variety of protocols such as TCP/IP.

On the other hand, WWW is just one of the ways that information can be disseminated over the Internet. Some of the other services provided on the Internet are: E-Mail, Instant Messaging and File Sharing. So, the Web is just a portion of the Internet.

Web Site & Web Portal:

A web site is a document in the hypertext form. It possesses text, files, databases, voice clips, video clips, etc. It is used as an access point to other sites in the Internet. The web has now over one million web sites and over 1.4 billion web pages.

A web portal is a web site that hosts on a huge web server. It has a large knowledge base. Its presentation is artistic. It has a specific theme and aim. It offers the usual services like Site Document service, Search facility, E-Mail service and User Registration etc.

The major difference between a web site and a web portal is that a web site provides services to all, whereas a web portal provides Internet services to a specific group of users, for instance, students, job-seekers, doctors, music-lovers and health cautious persons.

Services available on the Net:

Presently, many services are available through the Internet. Some of them are as follows:

1. E-Mail
2. World Wide Web
3. FTP and Anonymous FTP
4. Telnet
5. News and USENET
6. The Gopher
7. Wide Area Information Service (WAIS)
8. Internet Relay Chat (IRC)
9. VOIP
10. WAP
11. Web Casting of Video and
12. E-Com

Continue reading →

Introduction to Web Server!

WEB SERVER! 

A Web Server is a special software, which usually runs on a remote machine and responds to client requests by providing resources like HTML documents.  Requests are made by the client, which is a browser running on a local machine, using the address typed by the user (called Uniform Resource Locator – URL).  The web server maps the URL to a file on the server (or to a file on the server’s network) and returns the result in the form of HTML document to the client.

During interaction, the web server and the client communicate using Hyper Text Transfer Protocol (HTTP).  HTTP is platform independent protocol used for transferring requests and responses between a client and a server over the Internet.  There are two most common HTTP request types (methods): Get and Post.  Using get and post, we can send and receive data from a web server.  Among the two, the get request is for retrieving some static web page (stored in .html files) from the web server, whereas the post request retrieves a dynamic web page from the web server (by running a file such as .asp file).

A web server is a computer program that is responsible for accepting HTTP requests from clients (known as web browsers), and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and linked objects (images etc.).

HTTP Request Types:

The HTTP Request types – get and post - send form data to a web server and also  request for the appropriate resource from the server.  Though they work similarly, they differ in the way they send form data to a web server.

A get request sends form content as part of the URL.  For e.g.,

www.mail.yahoo.com/Welcome.asp?username=david@password=xyz

is a get request that sends username and password as parameter strings with the URL mail.yahoo.com.  In this request, the information following the symbol ? (username=david@password=xyz) indicates the user-specified input.

Get HTTP	Post HTTP
Used to get static web pages from the Server.	Used to get dynamic web pages with the help of server-side scripting.
Sends form data as a query string followed by ? in the URL	Sends form data as such in a form object that could be retrieved through Form collection in the Response object.
Limits the user query to 1024 characters.	No limitation of user input in the form.
Caches the web pages sent in response to the get request from the server.	Server’s response to the post request in the form of a web page is not cached.

Table: Difference between the use of Get and Post request

            A get request limits the user query to 1024 characters.  If it exceeds this limit, the post request is used.  The HTTP post request often post data to a server-side form handler, which is often an .asp file that fetches the data from a database residing at the server.  The data are processed by the script to generate a HTML file that host the data.  The HTML file is then sent back to the client as a response to the post request,  which will be displayed in the web server.

            Browsers often cache (save on a local disk) web pages for quick reloading to reduce the amount of data that the browser needs to download.  However, browser typically doesn't cache the server's response to a post request, because the next post request may not contain the same information.

Apache Web Server:

Apache is server software which runs on platforms like UNIX, Linux and Windows.  It is an open source product developed and maintained by the Apache Software Foundation.  This is the most popular web server because of its stability, efficiency and portability.

The Apache Web Server is modular.  There is a core Apache that deals with requests for files, HTTP content negotiation, debugging and tracing.  Some modules are incorporated by default; other modules are only added on request.  Such extension modules include the following:

1.      Modules with Perl and PHP interpreters

2.      The module for Source and Socket Layer (SSL) communications

Select the modules that are required and then build the Apache Server during installation.

The Apache web server is scalable.  That means, it can run on computers ranging from PC to Mid-range and Mainframe computers.  It can be configured to run on a typical home/office PC, on a multi-CPU Server and on an IBM’s Server computer.  Moreover, Apache deals with the full HTTP protocol.  It can handle content negotiation and authorization.

Apache’s Core Functionalities:

The Apache server has a relatively small core that can handle HTTP ‘Get’ requests for static pages and modules that provide all the other services of a full
HTTP-complaint server.  The default configuration for an Apache server incorporates the modules for the following:

1.      Dynamic pages (CGI & SSI)

2.      Controlled access to resources

3.      Content negotiation

            The Windows version of Apache has a large fixed part that incorporates many of the standard modules; the remaining modules are available as DLLs.

A Video on Accessing the Web Server over the Internet!

Continue reading →

Basic Internet Terminology!

BASIC INTERNET TERMINOLOGY! 

Internet Backbone

The internet backbone was funded and managed by the National Science Foundation (NSF) during the 1980s and early 1990s. In 1991, numerous privately owned long-distance connections were established on the backbone. And in 1995, NSF withdrew completely from internet oversight.

Prior to NSF, the Defense Advanced Research Projects Agency (DARPA) developed and monitored the communication system that would become the modern internet.
 
Internet Service Provider:

Corporate computers connect to the internet through a pc known as a gateway. The gateway establishes the connection to the internet service provider, or ISP. Home computer users are able to connect to their ISP directly, or through a router if a home network is in place.

Internet Connection:

Connection types are numerous. Integrated Services Digital Network (ISDN) and Digital Subscriber Line (DSL) offer high speed internet connection. Dial-up technology, using a modem is the traditional, and much slower, method of internet connection. ISDN and DSL are always on technologies, meaning that they are always connected to the ISP.

Dial-up establishes a connection for the duration of use, then terminates the session, much like hanging up at the end of a telephone conversation. The establishment of the connection between the modem and ISP is sometimes called the handshake.

Network Protocols:

Network protocols determine how information is transmitted from one network computer to another. This communication is essential to many networking applications, including the Internet, Email and World Wide Web, as well as mobile telephony and home networking.  The functions governed by protocols include the following:

1.      Determines which computer will transmit first and the way in which data is to be sent - in packets, bits, or blocks and how many.

2.      Keeps track of the network details like which computer sent the packet and whose turn it is to transmit.

3.      Checks whether or not an error has occurred during transmission.  If there is an error does the entire transmission need to be re-sent.

4.      Finds out if the message is allowed to access applications, and which ones.

5.      Keeps track of the priority of the packet.

TCP/IP:

TCP/IP is the network protocol used to communicate between computers on the internet. TCP/IP governs the messages sent and received. Other protocols include Ethernet and Token Ring. However, those are used within a LAN. TCP/IP is the internet standard.  TCP/IP is typically used to transmit between networks, from one LAN to another, or on a WAN. Within a LAN, Ethernet and Token Ring are more common architectures.

IP Addresses:

IP, or internet protocol is the format used to transmit data between computers on the internet.  Every network computer using TCP/IP is assigned an address.  IP addresses are formatted in 32-bit numeric addresses written as four numbers separated by periods. Each number in the address can be from zero to 255. For example, 0.0.255.255.

Human users do not typically use IP addresses directly, instead entering domain names of the computers they wish to visit. For example, www.suite101.com is a domain name.
Private addresses can be assigned by the network administrator. Using private addresses within an organization can be advantageous by aiding in the protection of network devices from hackers residing outside the firewall who do not know the addresses of devices they would like to reach.

Network Hub:

The network hub will be either a router or a repeater configuration. A repeater expands the boundaries of the existing network by repeating the signal. The router routes the packet to the correct destination, directly or via another router.

Wireless Network or Wi-Fi:

Wireless networks are able to connect to the internet, in addition to traditional land line methodologies. Wireless access can be achieved via a cellular phone, laptop with a wireless modem, or a wireless router. 

Wireless networks are also known as wireless local area networks - WLANS - or Wi-Fi.  The use of Wi-Fi in the home reduces or eliminates the problem of poor cellular service inside buildings.

Cloud Computing:

The high availability and flexible architecture of the internet allow for concepts such as cloud computing to be implemented by home users and corporations. Users are able to access their documents from any computer connected to the internet, rather than having to transport their data with them on a laptop, usb drive, or other device.

Continue reading →

Getting Connected to Internet!

GETTING CONNECTED TO INTERNET! 

From a technical point of view the Internet is a collection of thousands of networks, distributed throughout the world, that agree to communicate using certain rules or protocols.

Each site on the Internet has a unique numeric address called its IP address and usually a corresponding name called the domain name.  Information is passed around the Internet in packets.  Each packet contains the address of the sender and the address of the destination.

The packets can take different paths through the Internet.  It’s up to the software at the destination to receive the packets and reassemble them.  The emphasis is placed on the packets, not on the connections between systems.  Users generally access sites by giving a domain name; the hardware and software convert a domain name to an IP address.

A Video about How the Internet Works!

IP Address:


Every computer on the Internet is identified with an address, called Internet Address or Internet Protocol Address (IP Address).  IP Address is a number that uniquely identifies each computer on the net.  Each of these addresses is of four bytes.  Each byte is used for forming an integer.  The numbers are ranging from 0 to 255 in decimal (i.e., 00 to FF in hexadecimal).

The four numbers in an IP address are separated by dots in between them.  Hence, an IP address is written as, for example, 150.80.0.231.  We often refer to them as a sequence of four numbers between 0 and 255 separated by dots (.).  This makes them easier to number, because they are not randomly assigned, but hierarchically assigned.

Client/Server Model:

Many of the services operate according to a client/server model.  A program called the client (for instance, web browser) is started on one system and contacts a program called the server (for instance, IIS or Apache) at another computer on the Internet.  The client sends the commands typed or given by a user to the server. The server sends a reply to the client, and the client presents the information to the user.

All information on the Internet is in digital format.  This includes text, programs, charts, images, graphics, video, and audio.  When using the WWW we work in a hypertext or hypermedia environment.

A Uniform Resource Locator (URL) specifies items, services, and resources.  These are used by Web browsers to specify the type of Internet service or protocol to use and the location of the item.

Uniform Resource Locator:

Uniform Resource Locator (URL) is one type of Internet address, using which we can specify the address (i.e, location) of a web page.  Each web page on the Internet is associated with a unique URL.  URL usually begins with http://, which stands for Hyper Text Transfer Protocol, the industry standard for transferring web documents over the Internet.

The URL for the Web page "Abraham Lincoln: Internet Resources from the Library of Congress," for example, is http://lcweb2.loc.gov/ammem/alhtml/alrel.html. The protocol or service in this case is HTTP, or Hypertext Transfer Protocol, and a Web browser using it would contact the Internet site lcweb2.loc.gov and access a document named alrel.html.  The documents on the WWW are called Web pages.  These are written and constructed using a language or set of rules called Hypertext Markup Language (HTML).

The URLs of the web sites that handle private information, such as credit card number, often begin with https://, which is the abbreviation for Secure Hyper Text Transfer Protocol (https), the standard for transferring encrypted data over the Internet.

Basic requirements for Internet:


To get connected to the Internet, we need a connecting device such as modem or Network Interface Card (NIC) and a connection to an Internet Service Provide (ISP).  A Modem is a hardware that enables a computer to connect to the Internet.  Its primary task is to convert the digital data to audio tones that can be sent transmitted over the phone lines.  The received analog data are then converted back to the digital data for further processing.

A Network Card, also called Network Interface Card (NIC) is a hardware that allows a computer to connect to the Internet through a network or a high-speed internet connection, such as Local Area Network (LAN), cable modem or Digital Subscriber Line (DSL).  After ensuring that our computer has a modem or a Network Interface Card, the next step is to register with an Internet Service Provider (ISP).

Now, we can access the Internet by having a direct connection from our computer to a network.  This is often the case when our company or campus has a network installed in offices, classrooms, labs, or residence hall rooms.  To get connected to the Internet we’ll need the proper device to connect to our organization’s network and (possibly) the IP address for our computer and for a domain name system.

Another way to connect to the Internet is to use a modem to call an Internet service provider (ISP) and gain access through a PPP (Point-to-Point Protocol) connection.  In either case you may have to configure an email client and Usenet news client to handle incoming and outgoing email and reading and posting messages to Usenet newsgroups.

Dial-up Connections:

Dial-up connections are slow internet connections that make use of existing telephone lines for transmission.  If a computer is connected to the Internet using this type of inter connection, the user can’t receive voice calls via the telephone line while accessing the net.  If the voice calls do connect, the Internet connection is interrupted.  To prevent this, users often install an extra phone line dedicated to Internet service.

Broadband Connections:


Bandwidth refers to the amount of data that can be transferred through a communication medium in a fixed amount of time.  Different ISPs offer different types of high-speed connections, called broadband connections, which include DSL, cable modem and Integrated Services Digital Network (ISDN), each of which has a different bandwidth.

Broadband connection is a high-bandwidth Internet service that is most often provided to home users by cable television and telephone companies.  DSL is one type of broadband service that allows computes to have access to the Internet all the time through existing phone lines, without interfering with telephone services.  However, DSL requires a special modem provided by the ISP.

Like DSL, cable modems also enable the computer to access the Internet at all times.  Cable modems transmit data over the cables that bring television to homes and business.  Unlike DSL, the bandwidth is shared by many users in cable modem.  This sharing can reduce the bandwidth available to each user when many use the Internet simultaneously.

ISDN is also a broad-band connection, which provides Internet service over either digital or standard telephone lines.  To avail this type of high-speed connection, we need to have a special hardware, called a Terminal Adaptor (TA), which is usually obtained from the IP.

Continue reading →

Internet & Its Use!

INTERNET & ITS USE! 

Internet is a worldwide, publicly accessible network of interconnected computer networks that allows sharing or networking of files and information at remote sites from other academic institutions, research institutes, private companies, government agencies and individuals using the Transmission Control Protocol or Internet Protocol.  It is an essential medium for communicating and interacting with people worldwide, and to access the tremendous amount of information available on it.  Millions of people use internet everyday for business transactions or for personal use.

Internet and WWW:

Internet refers to the hardware and the media used for forming a global and grand computer network, called the Network of Networks.  Internet is a global network, which links a large number of autonomous systems, Intranets, Local Area Networks (LAN), Metropolitan Area Networks (MAN), and Wide Area Network (WAN).  No organization owns and controls the Internet.  But, it operates in the public domain.

On the other hand, World Wide Web (WWW) is just one of the ways information can be disseminated over the Internet.  Other ways of sharing and viewing information over the Internet are: e-mailing, instant messaging, file sharing etc.  Therefore, WWW is considered as an application that runs on the Internet.

Web Site and Web Portal:

A web site is a document in hypertext form, which includes text, graphics, voice-clips and video-clips.  It provides access points to other sites on the Internet.  The World Wide Web comprises of over one million web sites and over 1.4 billion web pages.

A web portal is a web site hosted on a huge web server.  It has a large knowledge base.  Its presentation is artistic.  It has a specific theme and aim.  It offers the usual services like site documents service, e-mail service, search engine, user registration etc.  It provides all these Internet services to specific group users such as students, job-seekers, doctors, music-lovers, and health conscious persons.

To attend a Quiz on WWW & Internet click here...

Services provided on the Internet

Presently, many services are available through the Internet.  Some of them are as follows:

1.      E-mail

2.      World Wide Web

3.      File Transfer and anonymous File Transfer

4.      Telnet

5.      News and USENET

6.      The Gopher

7.      Wide Area Information Service (WAIS)

8.      Internet Relay Chat (IRC)

9.      Web casting of Video

10.  e-Commerce

E-Mail:

Electronic mail or e-mail, is one of the most important services provided on the Internet.  About 5% of all usage of the Internet is for e-mail messages.  The only requirement for e-mailing between two parties (sender and receiver) is that they need to have an account with their respective ISPs for availing this service.

Searching the Internet:

The Internet provides a wealth of information on virtually any topic.  To help users locate information, many web sites provide search engine that explore the Internet and maintain searchable records containing information about web site content.  When the user enters a word or phrase, the search engine returns a list of hyperlinks to sites that satisfy the search criteria.

Search engines such as Google, Yahoo, AlltheWeb, AltaVisa and Lycos store information in data repositories called databases that facilitate quick information retrieval.  Each search-engine site has different criteria for narrowing searches, such as publishing data, language and relevance.  With multiple search engine, users are provided with best results while searching for some desired content. 

Sites such as MSN (www.msn.com) and Metacrawler (www.metacrawler.com) use meta-search engines, which do not maintain databases.  Instead, they send the search criteria to other search engines and aggregate the result.  The search results appear as hyperlinks in a search window.  Clicking a hyperlink in the search window loads the web page at that URL into the content window.

 A Demo on Browsing the Internet using a Browser like Internet Explorer!

Continue reading →

Multi-tier Architecture

MULTI-TIER ARCHITECTURE

A Web Server is special software, which usually runs on a remote machine and responds to client requests by providing resources like HTML documents. Requests are made by the client, which is a browser running on a local machine using the address typed by the user (called Uniform Resource Locator – URL). The web server maps the URL to a file on the server (or to a file on the server’s network) and returns the result in the form of HTML document to the client.

During the interaction, the web server and the client communicate using the platform independent Hyper Text Transfer Protocol (HTTP), a protocol for transferring requests and files over the Internet. There are two most common HTTP request types (methods): Get and Post. These request types send and receive data from a web server. Generally, the get request is for retrieving some resources from the web server, whereas the post request updates the contest of a web browser.

System Architecture:

A web server is software, which is running as part of a multi-tier application (sometimes referred to as n-tier application). The Multi-tier architecture divides the functionality of a web application into separate tiers (i.e., logical groupings of functionality). There are three major tiers in a multi-tier application: information tier, middle tier and the client tier. These tiers can be located on the same computer or on separate computers.

The information tier (also called the data tier or the bottom tier) maintains data for the application. This tier typically stores data in a RDBMS database. For e.g., a retail store may have a database for product information such as descriptions, prices and quantities in stock.

The middle tier implements logic like business logic and presentation logic that control interaction between application client and application data. This tier acts as an intermediary between data in the information tier and the application clients. Its duty is to process the clients’ requests from the top tier (e.g., a request to view a product catalog) and retrieves data from the database. Then, the retrieved data are processed and presented to the client as a web page by the presentation logic.

Business logic in the middle tier enforces business rules and ensures that data are reliable before updating the database or presenting data to the user. It applies business rules that dictate how clients can and can’t access application data and how applications process data.

The client tier or top tier is the client application, which is usually a browser. Users interact directly with a browser through its application window. The client interacts with the middle tier to make request and to retrieve data from the information tier.

Client-side Scripting vs. Server-side Scripting:

Client-side scripting is done using scripting languages like JavaScript, VBScript, HTML and DHTML. Such scripts are stored in the web page itself and sent to the client side for their execution by the Web Browser. The user of the web page can open and see the coding and alter it if they want. Client-side scripting is responsible for the following activities:

1. Validating the user input.
2. Accessing the browser and
3. Enhancing web pages with ActiveX controls and Java programs that run on a browser

The client-side validation reduces the number of requests that need to be passed to the server. Interactivity allows users to make decisions, click buttons and play games with out server interaction. Client-side scripts can access the browser, use features specific to that browser and manipulate browser documents. To conserve server resources and minimize internet traffic and delays, perform as much as processing as possible on the client.

Server-side Scripting:

Scripts that execute on a server and generate web pages dynamically as responses to the client request are known as server-side scripts. Programmers have greater flexibility when using server-side scripts. Server side script often queries the database in response to the client’s request, dynamically generates HTML pages containing the data of request and sends the pages to the client. Server-side scripts are not visible to the client.

Server-side scripts are written using languages such as ASP and JavaServlets, which are having wider range of programming capabilities than their client-side equivalents. For e.g., server-side scripts can access the server’s file directory structure, whereas client-side scripts can’t access the client’s file directory.

Server-side scripts also have access to server-side software that extends server functionality. These pieces of software are called ActiveX components for MS web servers and modules for Apache web servers.

Accessing Web Services:

Web servers are of two types: local web server and remote web server. Local web server is server software like PWS or IIS that runs on the current machine, which also runs the browser software. Whereas, a remote web server is server software like IIS or Apache, which generally runs on a machine connected in the same network or another network in the Internet.

To request a document from a web server, users must know the machine name (called host name) on which the web server software resides. Local web servers can be accessed either using the machine name or through an ID called host name (also called localhost) that refers to the local machine hosting the web server software.

To access a remote web server, which runs on the same network, we can make use of the network ID of the machine hosting the web server (called hostname). But, to access a server, which runs on another network connection in the internet, we need to have a different ID called Domain Name or IP Address that refers to the network which hosts the web server.

Continue reading →

Introduction to World Wide Web & Internet

WWW & INTERNET!

WWW is a system of interlinked, hypertext documents accessed via the Internet. It was created in 1989 by Sir Tim Berners Lee, working at CERN in Geneva, Switzerland. The WWW is a system of Internet Servers that support specially formatted documents. The documents are formatted in a markup language called HTML that supports links to other documents, as well as graphics, audio and video files.

Video Presentation on the The History of Internet

With a Web Browser, user views web pages that contain text, images, videos and other multimedia and navigates between them, using hyperlinks. There are several Web Browsers available now days; two of them are Netscape Navigator and Microsoft Internet Explorer. The Internet and WWW are not one and the same but two separate but related things.

The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of language known as Protocols.

Video Presentation explaining TCP/IP Model of Communication

The WWW, or simply Web, is a way of accessing information over the medium of Internet. It is an information sharing model that is built on top of the Internet. The Web uses HTTP protocol to transmit data over the Internet. The Web also utilizes browsers, such as IE or Netscape to access web documents called web pages that are lined to each other via hyperlinks.

The Web is just one of the ways that information can be disseminated over the Internet. The Internet is also used for E-Mail, which relies on SMTP, Usenet Newsgroups, Instant Messaging and FTP. So, the Web is just a portion of the Internet.

Video Presentation on the Working Principle of Internet!

Local Server and Remote Server:

              A web server is a computer program that is responsible for accepting HTTP requests from clients (known as web browsers), and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and linked objects (images etc.).

A host is a computer, which is connected to a network. Local host is a machine which is connected in a Local Area Network (LAN). A computer connected to a LAN can be accessed using its unique ID within the network. It is done with the help of the ID available in the Network Interface Card (NIC). Hence, to access a web page available in a local host, we can use either the host name or the host ID.

A remote host is a machine, which is connected to another network in the internet. To access a remote host, we need two names: a domain name and a host name. The domain name is a name that refers to a geographical area or the type of organization or business to which the particular host belongs to. But, the host name identifies the computer that host the web server within the specified domain.

Presentation that distinguishes the term Internet and WWW

Domain Name and IP Address:

A domain name represents a group of host on the Internet. It combines with a host name and a Top-Level Domain (TLD) to form a fully qualified host name. It provides a user-friendly approach to identify a site on the Internet. The TLD often describes the domain area, which may be one of the following:

.com - refers to a commercial business

.org - refers to a non-profit organization

.cn, .et, .om, .us, .in - refers to a country (called country domain)

Each fully qualified host name is assigned a unique address called an IP Address, which actually identifies a particular computer on the Internet. A Domain Name Server (DNS) is a computer that maintains a database of host names and their corresponding IP addresses, and translates the fully qualified host name to an IP address. The translation operation is referred to as a DNS lookup. For e.g., the web address www.deitel.com is translated into an IP address of the Deitel web server (i.e., 207.60.134.2300.

Continue reading →