What is a Proxy Server?

 

Mei Ling Lee

A proxy server is an application running on a computer that sits between a Web browser and a Web server, and it usually resides on the same network as its user. You may like to think of the proxy server as the Random Access Memory (RAM) and the remote Web server as the hard disk in your PC. Needless to say, the speed of retrieving data from RAM is considerably faster than that from disk. Proxy server works in a similar fashion. It intercepts all users’ requests of Web pages to see if it can fulfil the requests itself without first going directly to the distant Web server. If not, it then forwards the requests to the Web server. Obviously, it can improve performance dramatically by fetching common Web pages from a local computer for our users.

Imagine the case where a lecturer Jack and a student Jill both access the World Wide Web through a proxy server. First Jack requests a Web page from a Web server in Canada, say Page X. The proxy server intercepts the request and checks if it has a copy of this page itself. As it does not possess a copy, it goes to the Web server in Canada to retrieve that page which can be very time-consuming. When the page is received, it delivers to Jack's Web browser and at the same time retains a copy of it for a certain period of time. If some time later, Jill requests the same page. Instead of forwarding the request to the remote server where Page X resides, the proxy server simply returns Page X that it has saved earlier. Not only is it a much faster operation, it is also a cost-effective one.

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