Introduction to Web Servers

A web server is a combination of the two things a computer machine and software installed on it such as Apache and IIS to process the HTTP requests from the client browsers.  A web server is also known as the HTTP server.  Client’s software (browser) sends a request to the web server for the specific page and if the web server finds this page it sends back to the browser, which then displays it at the client computer.  Every web server has a unique IP address and they allocate a unique or shared IP addresses to the websites they host. Apache web server software is the most popular web server followed by the Microsoft’s IIS (Internet Information Server).  When you browsers send out a request for the specific website like theitlibrary.com, your browse sends the request for the theitlibrary.com IP address. 

This request also includes the return information. When the web server receives the request it process the request and sends out the page in the HTML code to your IP address. Your browser interprets the HTML and displays the graphical website on your computer. The more powerful is your server and faster it serves out the requests.  Every computer on the internet that hosts a website must have a unique IP address and the web server software like Apache and IIS.  Before choosing a web server you need to know it’s compatibility with the operating system, it’s capability to handle the server side programming, response time, reliability, error handling and the security characteristics.

Any computer with the web server software and permanent connectivity with the internet can act as a web server.  All the web server software share the common characteristics such as handling HTTP requests, authentication, logging, virtual hosting, content compression, large files support, support for databases, session tracking, storing information about clients and, SSL support, password protection,  URL rewriting, great performance and  security features.  Sometimes web server overloads or their response time decreases badly due to the following reasons.

• Computer Viruses or worms
• DDOS attacks
• Internet web roots.
• Internet network slows down
• Too much legitimate web traffic at the same time
• XSS viruses

Web Server Overload Symptoms

• Requests are served with the noticeable long delays.
• Overloaded web servers returns the 500, 502, 503, 504 HTTP errors to returned to clients.  Sometimes error 404 and 408 are also returned.

The overloading of the web servers can be partially overcome by using the firewall, HTTP traffic managers (to drop, redirect and rewrite the requests),  managing the bandwidth, adding more hardware resources, using load balancers (many web server computers that are grouped together) and deploying web cache techniques.