Apex domains cannot have CNAME records.
Question and response
Question
dig opentur.it. NS
Answer
opentur.it. 5 NS pns11.cloudns.net.
opentur.it. 5 NS pns13.cloudns.net.
opentur.it. 5 NS pns12.cloudns.net.
opentur.it. 5 NS pns14.cloudns.net.
opentur.it. 5 NS cloud-ns1.opentur.it.
opentur.it. 5 NS cloud-corner.opentur.it.
Authority
The response has no authority records.
Additional
cloud-corner.opentur.it. 5 A 141.147.15.245
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0