You can use zfbot.com to research domain name.
Find the name servers following the instructions here: http://anonit.blogspot.com/2015/06/to-lookup-dns-records-for-domain-name.html.
Enter the name server and enter the domain query. EG: Enter a primary name server of ‘a.ns.facebook.com’ and enter ‘facebook’ in Starts:
You can then see a list of domains that facebook has listed on their name servers.
This works with any domain. EG: nameserver ns35.domaincontrol.com and anonit.