Apex domains cannot have CNAME records.
Question and response
Question
dig cobytes.eu. NS
Answer
cobytes.eu. 5 NS ns1.cobytes.io.
cobytes.eu. 5 NS ns2.cobytes.com.
cobytes.eu. 5 NS ns3.cobytes.eu.
Authority
The response has no authority records.
Additional
ns1.cobytes.io. 5 A 185.71.62.53
ns2.cobytes.com. 5 A 5.75.236.16
ns3.cobytes.eu. 5 A 193.111.32.53
ns1.cobytes.io. 5 AAAA 2a03:38a0:62:53:0:0:0:1
ns2.cobytes.com. 5 AAAA 2a01:4f8:c012:7d6b:0:0:0:1
ns3.cobytes.eu. 5 AAAA 2a0f:8cc0:0:32:53:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0