When you're developing an Android App you'll most likely want to give someone - the customers and/or beta-testers, colleagues, etc - an URL pointing to an .APK file not (yet) present in the Google Store Market. Since the vast majority of web servers (including IIS) don't natively support the .apk MIME-type, your URL will most likely give an apparently odd 404 - Page Not Found error response. In order to overcome the problem you need to add the proper MIME-type corresponding to .apk file in the following way:
- Open the IIS Administration Panel (see picture).
- In the left panel, click to the entry corresponding to your global IIS instance (pt. 1 in picture) so that each modification you'll make will be applied to all your past, present and future web-sites. If you only want to handle the .apk MIME-type for a specific web site, click to the entry corresponding to it instead.
- In the right panel, Click to the "MIME Types" icon. You will be presented with a listing of all currently supported MIME-types.
- Click to the "Add..." button near the top-right corner (pt. 2 in picture) and add the following MIME-type (pt. 3 in picture):
- Extension: .apk (be sure to include the dot)
- MIME-type: application/vnd.android.package-archive
(click over the picture to enlarge)
Needless to say, this can be used to allow the download of any other file extension.
If you're not using the IIS Management interface and/or if you want to work directly on web.config level you can achieve the same result by following the comprehensive instruction explained in the official IIS configuration page.
While you're at it, if you're willing to do the same thing with iOS .ipa files you can check this post and wrap it up aswell. If you also need to enable it for Windows Phone's .xap files, check this post instead.