Apex domains cannot have CNAME records.
Question and response
Question
dig attiva.biz. NS
Answer
attiva.biz. 5 NS dns5.interbusiness.it.
attiva.biz. 5 NS dns4.interbusiness.it.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0