mtas.spf.srv.isp.hu has no CNAME records.
Question and response
Question
dig mtas.spf.srv.isp.hu. NS
Answer
The response has no answer records.
Authority
isp.hu. 10800 SOA nsa1.isp.hu. dnsadmin.isp.hu. 2025120502 43200 10400 1814400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0