We pick i.root-servers.net, one of the 13 root servers (1), and ask it about mzs.it and learn that it is delegated to six name servers (2), so we ask c.dns.it where we learn that mzs.it is delegated to two name servers, including nameserver.rm.cnr.it (3), so we ask that one and get the following answer:
Mzs.it is a domain controlled by two domain name servers at cnr.it. Both are on the same IP network. Mzs.it has one IP number (150.146.0.254), but no corresponding reverse pointer.
Twelve of them use name server group 1. Worth noting is that twelve of the domains that use name server group 1 use the primary name server nameserver.rm.cnr.it.
Three of them use the two name servers dns2.cnr.it and nameserver.rm.cnr.it together, hereafter referred to as "name server group 3". Worth noting is that all of the domains that use name server group 3 use the primary name server nameserver.rm.cnr.it.
The two name servers nameserver.rm.cnr.it and dns.sic.rm.cnr.it together
There are three domains that use the two name servers nameserver.rm.cnr.it and dns.sic.rm.cnr.it together, hereafter referred to as "name server group 4".