We pick f.root-servers.net, one of the 13 root servers (1), and ask it about h.pn and learn that pn is delegated to four name servers (2), so we ask ns0.pitcairn.net.pn where we learn that h.pn is delegated to two name servers, including ns3.mailart.com (3), so we ask that one and get the following answer:
H.pn is a domain controlled by two domain name servers at mailart.com. Both are on the same IP network. Incoming mail for h.pn is handled by one mail server at h.pn themselves. H.pn has one IP number (180.42.26.116), but the reverse is ?.
H.pn is hosted on a server in Tokyo, 40, Japan even though the hostname implies Pitcairn.
The name server ns2.mailart.com
There are several hundred of domains that use the name server ns2.mailart.com.
All of those use the two name servers ns2 and ns3.mailart.com together, hereafter referred to as "name server group 1", (example: f.kz, c9.cc and ff.mw ).