IPAddressToDomain SharedNS
From Paterva Wiki
This transform queries two 'historical' DNS providers (Serversniff and Robtex) to determine if this IP address is the also used by other domains as an NS record. This type of 'reverse NS lookup' cannot be performed using standard DNS queries and is very useful to find other domains associated with the IP number. In most cases one would work from the actual DNS name of the NS record, but if you only have the IP address available there is no standard way of knowing if the IP address is an NS for a domain or not. This transform gives you the ability to do this. Unlike the 'reverse MX lookup' the 'reverse NS lookup' does not always imply that the domains found have a close relationship with the IP address as many companies and organizations outsource their DNS service.