CORS preflight request returning HTTP 401 with windows authentication

Here is the solution that uses "URL Rewrite" IIS module. It works perfectly.

1- Stop IIS service (maybe not necessary)

2- Install "web platform installer" from https://www.microsoft.com/web/downloads/platform.aspx

3- Go to "Applications" tab and search for "URL Rewrite" and download it

4- Install this hotfix KB2749660 (maybe not necessary)

5- Open IIS configuration tool, double click "URL Rewrite"

6- Add a new blankrule

7- Give it any name

8- In "Match URL", specify this pattern: .*

9- In "Conditions", specify this condition entry: {REQUEST_METHOD} and this pattern: ^OPTIONS$

10- In "Action", specify: action type Personalized response, state code 200, reason Preflight, description Preflight

11- Start the server

Now, the server should reply with a 200 status code response to the preflight request, regardless of the authentication.

Remarks: I also disabled all compression, I don't know if it matters.

From AhmadWabbi's answer, easy XML pasting into your web.config:

<system.webServer>
    <rewrite>
        <rules>
            <rule name="CORS Preflight Anonymous Authentication" stopProcessing="true">
                <match url=".*" />
                <conditions>
                    <add input="{REQUEST_METHOD}" pattern="^OPTIONS$" />
                </conditions>
                <action type="CustomResponse" statusCode="200" statusReason="Preflight" statusDescription="Preflight" />
            </rule>
        </rules>
    </rewrite>
</system.webServer>