How to configure HTTP response headers
HTTP headers are generally loaded automatically by the web server, so the website administrator really never has to worry about checking on them. In some cases however, an exception has to be made to ensure that the website can be compatibly loaded for a specific client. In such cases, the website administrator can make an exception in the settings of the web server, for instance Apache or IIS.
If the webmaster doesn't have access to the server, let's say in a shared hosting environment, it's possible to insert a local header in a specific page, for example with a header() command in PHP or an AddHeadr() command in ASP.