Apex domains cannot have CNAME records.
Question and response
Question
dig dimensionesrl.eu. NS
Answer
dimensionesrl.eu. 5 NS dns1.dimensione.com.
dimensionesrl.eu. 5 NS dns2.dimensione.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0