I used to have Windows Authentication in-place and works like a charm!
The thing is, now I have a Sitecore 8.2 update 4 (rev. 170614) and Forms Authentication is enabled by default, and whenever I enable Windows Authentication IIS throws a warning
Challenge-based and login redirect-based authentication cannot be used simultanesously
So, I wonder how would it be possible to protect my Sitecore 8.2 update 4 from anonymous access and to avoid being indexed by search engines?