olemus
primaarse DNS-serveri konfiguratsioon,
mis muudab ta väliselt nähtamatuks
=
a special DNS configuration not publicly visible

RFC 7719:
a stealth server that is a master for zone transfers

ülevaateid
https://www.inetdaemon.com/tutorials/internet/dns/configuration/hidden_master.shtml

https://www.zytrax.com/books/dns/ch4/