We pick i.root-servers.net, one of the 13 root servers (1), and ask it about wwwgoogle.pl and learn that pl is delegated to eight name servers (2), so we ask c-dns.pl where we learn that wwwgoogle.pl is delegated to two name servers, including ns2.blaster.pl (3), so we ask that one and get the following answer:
Wwwgoogle.pl is a domain controlled by two domain name servers at blaster.pl. Both are on different IP networks. Incoming mail for wwwgoogle.pl is handled by two mail servers also at blaster.pl having a total of two IP numbers. Two mail servers have the same IP number. Both are on different IP networks. Wwwgoogle.pl has one IP number (194.28.49.140), but the reverse is ip-194.28.49.140.iwacom.net.pl.
The two name servers ns1 and ns2.blaster.pl together
There are almost a thousands domains that use name server group 1.
Three quarter of those use mail server group 1 (example: toyota.net.pl, 205-75r15.com and peugeot.net.pl ). Worth noting is that all of the domains that use mail server group 1 use name server group 1.
The two mail servers mx1 and mx2.blaster.pl together
There are several hundred of domains that use mail server group 1.
All of those use name server group 1 (example: gieldasamochodowa.net.pl, ratka.pl and 215-75r16c.com ). Worth noting is that three quarter of the domains that use name server group 1 use mail server group 1.
