I am looking for a reliable service that has a good database of the hosting providers vs domain names. I guess some of the domains that are privately hosted cannot be resolved to a definite hosting provider (maybe just to ISP).
I have used webhosting.info (their power whois and advanced whois) which used to give hosting information(not sure) earlier but not anymore. I looked at domaintools.com but couldnt find anything like that in their tools.
I guess I could do a reverse IP on a domain and go to arin.net and get the org name. But looking for a free (or paid service) that can do bulk lookups or any reverse dns tools that you recommend or use.
Majority of websites use DNS server provided by hosting company, but you can use any other DNS server to resolve your domain names. So looking up by IP address allocation data is the best method.
Here is a site which does it for you: