We pick d.root-servers.net, one of the 13 root servers (1), and ask it about ts.cnr.it and learn that it is delegated to six name servers (2), so we ask m.dns.it and get the following answer:
Ts.cnr.it is a domain controlled by four domain name servers at cnr.it and cineca.it having a total of four IP numbers. All four of them are on the same IP network. We are missing the IP:s of three servers: pdadr1.pd.cnr.it, adraxp.pd.cnr.it and nameserver.cnr.it. Incoming mail for ts.cnr.it is handled by one mail server at cnr.it having a total of one IP number. We are missing the IP:s of one server: pdadr1.pd.cnr.it.
There are five domains that only use the mail server pdadr1.pd.cnr.it.
All of those are under the tld "it".
Three of them use name server group 1. Worth noting is that three of the domains that use name server group 1 use only the mail server pdadr1.pd.cnr.it.
The four name servers dns.cineca.it, nameserver.cnr.it, adraxp.pd.cnr.it and pdadr1.pd.cnr.it toget…
There are five domains that use name server group 1.
Three of them use the primary mail server pdadr1.pd.cnr.it and the last resort mail server.
Three of them use only the mail server pdadr1.pd.cnr.it. Worth noting is that three of the domains that only use the mail server pdadr1.pd.cnr.it use name server group 1.