How to serve unknown file types from IIS 7

You can add an universal MIME type by using the extension "*" and the type "application/octet-stream": http://support.microsoft.com/kb/326965

Instead of going through the MMC like the kb article suggests, you can also just create a Web.config file in the directory, with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <staticContent>
            <mimeMap fileExtension=".*" mimeType="application/octet-stream" />
        </staticContent>
    </system.webServer>
</configuration>

Just in case pictures help. This is for IIS v10 installed on a windows 10 box:

1. Go to MIME Types feature of the virtual directory of your website:

2. Set up the asterisk based mime type to support unknown file types: