Apex domains cannot have CNAME records.
Question and response
Question
dig fastfone.it. NS
Answer
fastfone.it. 4 NS dns3.arubadns.net.
fastfone.it. 4 NS dns2.technorail.com.
fastfone.it. 4 NS dns.technorail.com.
fastfone.it. 4 NS dns4.arubadns.cz.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0