First off, I don't really know anything about mod_write. We had a client email us and ask if mod_rewrite was installed on our servers. I did am "http d -l" on the server shell, and it was not listed. However, if you load a phpinfo() page, mod_rewrite was listed in the loaded Apache modules. So, I contact our server provider and asked if they could clarify this. They said that if httpd -l did not list it, then it was not installed. I later ran a test, and put:

RewriteEngine On

in an .htaccess file, and tried to access the directory through a browser. I did not get an Internal Error or anything, the page loaded just fine. Is the mod_rewrite module installed? I don't know what to tell our client.