IIS Binding with windows authentication

Question

I have a local website (http://localhost/testsite) with Windows Authentication, that works well.

Now I changed the binding of the site to an URL (http://testsite.blablab

Answer 1

Note that by changing binding, this site may not be accessed again by your previous URL in web browsers. Learn about what is a binding and you should find out if you did something wrong.

So the site that gives you this 401.1 can be completely another site.