I have written a PHP script that I would like to use on several domains on the same server (pointing to same script). I want to add functionality to the script so I can find out which domain the script is working with at any time. HTTP_HOST can be used to find the domain ,however, I have read that its not reliable especially with older browsers. My understanding is most Apache servers use virtual hosts which uses the same method anyway so if its not a problem with hosting providers it shouldn't be an issue with my code.
Can any one please verify this and clear the confusion ?
HTTP_HOST is for the Host: header sent by HTTP 1.1 user-agents during the request. This is not used by HTTP 1.0 clients, so it won't appear then. However, nowadays, I don't think there are still many HTTP 1.0 clients.