Apex domains cannot have CNAME records.
Question and response
Question
dig aruba.it. NS
Answer
aruba.it. 1 NS arudns1.aruba.it.
aruba.it. 1 NS arudns4.aruba.it.
aruba.it. 1 NS arudns3.aruba.it.
aruba.it. 1 NS arudns2.aruba.it.
Authority
The response has no authority records.
Additional
arudns1.aruba.it. 1 A 94.177.210.15
arudns2.aruba.it. 1 A 95.110.136.13
arudns3.aruba.it. 1 A 95.110.220.15
arudns4.aruba.it. 1 A 81.2.199.101
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0