Apex domains cannot have CNAME records.
Question and response
Question
dig ehiweb.it. NS
Answer
ehiweb.it. 5 NS ns1.ehiweb.it.
ehiweb.it. 5 NS ns18.ehiweb.it.
ehiweb.it. 5 NS ns999.ehiweb.eu.
Authority
The response has no authority records.
Additional
ns1.ehiweb.it. 5 A 79.98.40.11
ns18.ehiweb.it. 5 A 79.98.45.16
ns1.ehiweb.it. 5 AAAA 2a01:b600:1:10:0:0:0:1
ns18.ehiweb.it. 5 AAAA 2a01:b600:1:61:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0