How to add a new file extension in IIS

MIME or Multipurpose Internet Mail Extensions is a set of specification for file formats. Although IIS (Internet Information Services) supports common file or mime types but many unique or non common files cannot be host on IIS, to host or use new file extension with IIS you should follow given steps.

NOTE: You can figure out easily if your server is configured to support desired file extension by posting that file on a server and navigating to the URL of that in a browser. If you see a LONG string of garbage on the screen or 404 not found error, your server isn't set up for that file and needs to have the MIME type set up.

Go to Start Menu » Administrative Tools » Internet Information Services, it will bring up IIS Snap-in. If Administrative Tools are not displaying in Start Menu refer to this article "Customize your Start Menu" or go to Control Panel and click on Administrative Tools.

Now IIS Snap-in is open, on the left pan "XXXX (local computer)", where XXXX is your computer/server name, click Web Sites and right click on any website (in my case it is gikso) and clickProperties.

Select HTTP Headers tab and click File Types (bottom right), it will bring up File Types window.

Click New Type and add new file type. Let me take .dmg file extension as example. Enter .dmg inAssociated extension and application/x-apple-diskimage in Content type (MIME) and press enter or click OK

New extension will be appear ... click OK twice and close IIS Snap-in, verify new extension by navigating to the file having .dmg file extension in a browser.