1. HOW WEB SERVER WORKS? By- PUSHPENDU MONDAL RAJAT CHAUHAN RAHUL YADAV RANJIT MEENA RAHUL TYAGI

2. When you open your web browser and type www.google.com on address bar. What happens?

4. INTRODUCTION Have you ever wondered about the mechanisms that delivered this page to you ? The answer is: NO So today there is a chance for you to know about how Web servers bring pages to your browser when you simply click on the link or type the URL on address bar.

5. WEB SERVER Web server is either the hardware (the computer) or the software (the computer application) that helps to deliver content that can be accessed through the Internet. The most common use of web servers is to host websites, but there are other uses such as gaming, data storage or running enterprise applications.

6. It's important to note that this is a two-sided story. Web servers are responsible for storing and exchanging information with other machines. At least two participants are required for each exchange of information: Client and Server. Client which requests the information. Server which stores the information. BEFORE WE START

7. Each side also requires a piece of software to negotiate the exchange of data. In the case of the client, a browser like Netscape or Internet Explorer is used. On the server side there are software options available, which have similar task: to negotiate data transfers between clients and servers via Hypertext Transfer Protocol, the communications protocol of the Web. Contd…

8. The type of server software you are able to run depends on the Operating System chosen for the server. For example, Microsoft Internet Information Server is a popular choice for Windows NT, while many Unix fans choose Apache Web server. Contd…

9. BASIC PROCESS

10. LET’S START IN DETAIL Firstly, when you typed the URL in the address bar or click on the link available on the web page. The browser breaks the URL into three parts: 1. The protocol ("http") 2. The server name ("www.google.com") 3. The file name ("web-server.htm")

11. A Domain Name Server (DNS) translates the domain name the user has entered in to its IP address into a numeric combination that represents the site's true address on the Internet. Example: google.com 66.249.64.0 - 66.249.95.255 209.85.128.0 - 209.85.255.255 216.239.32.0 - 216.239.63.255 SECOND STEP…

12. Google utilizes these multiple Internet servers to handle incoming requests to its Web site. Instead of entering http://www.google.com/ into the browser, you can enter http:// followed by one of the above addresses. For example: http://74.125.224.72/ (it will open the search engine Google). Contd…

13. PORTS: In computer networking a port is an application- specific or process-specific software construct serving as a communications endpoint in a computer's host operating system. It is associated with an IP address of the host, as well as the type of protocol used for communication. The protocols that primarily use the ports are Transmission Control Protocol and the User Datagram Protocol of the Internet Protocol Suite. Any server machine makes its services available to the Internet using numbered ports, one for each service that is available on the server. THIRD STEP

14. Contd… For example, if a server machine is running a Web server and an FTP server, the Web server would typically be available on port 80, and the FTP server would be available on port 21. Clients connect to a service at a specific IP address and on a specific port. Here are some common port numbers: 1. echo 7 2. daytime 13 3. ftp 21 4. telnet 23

15. Once a client has connected to a service on a particular port, it accesses the service using a specific protocol. The browser now determines which protocol (the language client machines use to communicate with servers) should be used. Examples of protocols include FTP, or File Transfer Protocol, and HTTP, Hypertext Transfer Protocol. FOURTH STEP…

16. The server sends a GET request to the Web server to retrieve the address it has been given. The most basic form of the protocol understood by an HTTP server involves just one command: GET For example, when a user types http://www.example.com/1.jpg, the browser sends a GET 1.jpg command to example.com and waits for a response. The server now responds to the browser's requests. FIFTH STEP…

17. Now it verifies that the given address exists. Then it finds the necessary files, runs the appropriate scripts, exchanges cookies if necessary. and Returns the results back to the browser. If it cannot locate the file, the server sends an error message to the client. Contd…

18. The browser translates the data it has been given in to HTML and displays the results to the user. This process is repeated until the client browser leaves the site. At last…

19. First, you type the URL on address bar of your web browser. The browser breaks the URL into three parts protocol, server name and file name. The browser communicates with a name server to translate the server name into an IP address, which it uses to connect to that server machine. The browser then forms a connection to the Web server at that IP address on port. SUMMARY

20. Following the HTTP protocol, the browser sends a GET request to the server, asking for the file. The server sends the HTML text for the Web page to the browser. The browser reads the HTML tags and formats the page onto your screen Contd…

21. THANK YOU