icinga2.masterinter.net has no CNAME records.
Question and response
Question
dig icinga2.masterinter.net. NS
Answer
The response has no answer records.
Authority
masterinter.net. 300 SOA ns1.master.cz. noc.master.cz. 2026032618 900 900 1800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0