Apex domains cannot have CNAME records.
Question and response
Question
dig gritalia.net. NS
Answer
gritalia.net. 5 NS ns-1117.awsdns-11.org.
gritalia.net. 5 NS ns-591.awsdns-09.net.
gritalia.net. 5 NS ns-161.awsdns-20.com.
gritalia.net. 5 NS ns-1297.awsdns-34.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0