Apex domains cannot have CNAME records.
Question and response
Question
dig prometeus.it. NS
Answer
prometeus.it. 2 NS c.0ns.eu.
prometeus.it. 2 NS nsit3.prometeus.it.
prometeus.it. 2 NS nsit2.prometeus.it.
prometeus.it. 2 NS b.0ns.eu.
prometeus.it. 2 NS a.0ns.eu.
prometeus.it. 2 NS nsit1.prometeus.it.
Authority
The response has no authority records.
Additional
a.0ns.eu. 3 A 195.88.5.1
b.0ns.eu. 3 A 162.250.147.7
c.0ns.eu. 3 A 185.136.176.100
nsit1.prometeus.it. 2 A 195.88.5.1
nsit2.prometeus.it. 2 A 194.71.225.121
nsit3.prometeus.it. 2 A 37.247.50.100
a.0ns.eu. 3 AAAA 2a00:dcc0:eda:2:195:88:5:1
b.0ns.eu. 3 AAAA 2a00:dcc7:d3ff:0:162:250:147:7
nsit2.prometeus.it. 2 AAAA 2a00:dcc7:d3ff:0:0:0:0:1210
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0