Apex domains cannot have CNAME records.
Question and response
Question
dig infocert.it. NS
Answer
infocert.it. 5 NS ns-1883.awsdns-43.co.uk.
infocert.it. 5 NS ns-756.awsdns-30.net.
infocert.it. 5 NS ns-56.awsdns-07.com.
infocert.it. 5 NS ns-1116.awsdns-11.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0