I have added .cer as application/x-x509-ca-cert
as a global MIME type in IIS7.5 on Windows 7 Professional x64 but it still refuses to use that MIME type and it continues to use text/html. It shows the MIME type as inherited in all my websites.
I've restarted, uninstalled and reinstalled IIS a million times and I have no friggin clue why .cer alone refuses to work. I've added other MIME types which work properly, but nothing I do can make .cer appear as ANYTHING other than text/html.