ns.grdns.it has no CNAME records.
Question and response
Question
dig ns.grdns.it. NS
Answer
The response has no answer records.
Authority
grdns.it. 3600 SOA ns.grdns.cz. admin.grdns.cz. 2020012101 3600 1800 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0