d4023.masterinter.net has no CNAME records.
Question and response
Question
dig d4023.masterinter.net. NS
Answer
The response has no answer records.
Authority
masterinter.net. 291 SOA ns1.master.cz. noc.master.cz. 2026032573 900 900 1800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0