Apex domains cannot have CNAME records.
Question and response
Question
dig imalserramenti.com. NS
Answer
imalserramenti.com. 2 NS ns-1100.awsdns-09.org.
imalserramenti.com. 2 NS ns-880.awsdns-46.net.
imalserramenti.com. 2 NS ns-249.awsdns-31.com.
imalserramenti.com. 2 NS ns-1220.awsdns-24.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0