Apex domains cannot have CNAME records.
Question and response
Question
dig eu-dcc-rome-1.ocs.psn-pco.it. NS
Answer
eu-dcc-rome-1.ocs.psn-pco.it. 5 NS ns1.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it.
eu-dcc-rome-1.ocs.psn-pco.it. 5 NS ns2.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it.
eu-dcc-rome-1.ocs.psn-pco.it. 5 NS ns3.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it.
Authority
The response has no authority records.
Additional
ns1.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it. 5 A 158.180.164.26
ns2.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it. 5 A 158.180.164.121
ns3.p200.dns.eu-dcc-rome-1.oci.psn-pco-realm.it. 5 A 158.180.164.77
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0