Well, what if I want to serve files without extensions on IIS 7?
A small test will give you a 404 error page, as this MIME type is not set up yet.
So, why not go and add one rule? What! How can I add such as rule, if the file has no extension!
Calm down. All you need is to use “.” (a single and easy DOT) in the extension field, and you are done.