Let's say I run a website
example.com with a dedicated IP
A.B.C.D. Then I find out doing a search on Google, that my website is also being indexed through a domain
A-B-C-D.example.com (where the
A-B-C-D is equivalent to the dedicated IP). Obviously this is seen as a duplicated content.
I don't have access to that second domain so I can't get rid of it (according to support team at the hosting company, that domain was set up as "rDNS" to the dedicated IP by a third party that manages the domain). How can I stop it from being indexed in Google while my main domain still is?