We pick c.root-servers.net, one of the 13 root servers (1), and ask it about arpa.gr and learn that gr is delegated to seven name servers (2), so we ask grdns.ics.forth.gr where we learn that arpa.gr is delegated to three name servers, including ns2.banet.net.gr (3), so we ask that one and get the following answer:
Arpa.gr is a domain controlled by two domain name servers at net.gr. Both are on the same IP network. Incoming mail for arpa.gr is handled by one mail server at arpa.gr themselves. Arpa.gr has one IP number (5.9.80.133), but the reverse is host90.godigital.gr.
A third of them use the three name servers ns1, ns2 and ns3.banet.net.gr together, hereafter referred to as "name server group 2", (example: kastrakicamping.gr, vitaslim.com and pbs.gr ). Worth noting is that most of the domains that use name server group 2 use the primary name server ns1.banet.net.gr.
The three name servers ns1, ns2 and ns3.banet.net.gr together
There are more than hundred domains that use name server group 2.
About one in six of them use only the IPv4 number 5.9.80.133 (example: iskra.gr and soufli.gr ). Worth noting is that more than one in seven of the domains that only use the IPv4 number 5.9.80.133 use name server group 2.