From Paterva Wiki
This transform uses a special type of DNSName - a NS record. It determines which other domains uses this DNS Name as an name server. This is very useful in the infrastructure footprint of an organisation as it can reveal other domains that the organisation uses. If company X's Domains all have NS records pointing to a single DNS name this transform can find all (or most) of these domains. A word of caution - if the target is hosting it's name servers at an ISP then you will end up with a list of domains that hosted by the ISP - normally not the most exciting result.
NSrecord via transform NSrecordToDomain_SharedNS to