I am new to PHP, and am running PHP on both Windows/IIS and on Linux/Apache. Please, no comments about the Windows/IIS....

It seems difficult for me to determine basic behavior of startup for a single domain. I want to set an auto_prepend_file value that applies only for one domain, not the whole server. I believe it is easy with Apache and that .htaccess is the right place. But, what is the equivalent in Windows? Is it a php.ini file in the web root of the domain? Or, the php.ini in the Windows main directory. I also worry that if I provide a php.ini in the domain web root it may nullify the php.ini in the Windows directory.

Any suggestions?