smtp21.hosttech.eu has no CNAME records.
Question and response
Question
dig smtp21.hosttech.eu. NS
Answer
The response has no answer records.
Authority
hosttech.eu. 10800 SOA ns1.hosttech.eu. abuse.hosttech.eu. 2026030345 7200 120 2419200 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0