Not able to download certain files.

I'm working on some automatic updating for my programs, and I have two files that I'm not able to download, even if I try and get them directly from the browser. It's like the file extensions are protected.

The two extensions I'm having problems with are .hst and .qdf... I get a file not found error... but if I change the extensions on the web server to .dll, .exe, or some other "known" extension, it works...

Is this a function of IIS not allowing those downloads, or is it a function of the browser? In either case, does anyone know how I could get it to download these files?

<edit>I just noticed that it seems that any "unknown" extension gets shown as file not found... like ".zzz"</edit>

Thanks
Bryan

Thought I could provide some more information and hopefully generate a response...

I have a configuration file that I use for one of my programs... the extension is one I made up (.enc) If I put this file on a web server and type in the address in the address bar (http://my.domain.tld/downloads/file.enc) it comes back as "The page cannot be found."... I need to be able to access these files directly, but even creating a link on another page doesn't work, even if I right click and select save target as... Is this a function of the client side browser, or the server side Web Server not allowing unknown extensions to be downloaded?

I found it, there is a registered mime types dialog in IIS admin that you can add more types to... these are used in the response headers to a client when they make a request for a file.

Thanks for posting your solution, I didn't know the answer.