Apex domains cannot have CNAME records.
Question and response
Question
dig oniaas.io. NS
Answer
oniaas.io. 5 NS ns2.oniaas.io.
oniaas.io. 5 NS ns1.oniaas.io.
Authority
The response has no authority records.
Additional
ns1.oniaas.io. 5 A 172.64.52.8
ns2.oniaas.io. 5 A 172.64.53.20
ns1.oniaas.io. 5 AAAA 2606:4700:52:0:0:0:ac40:3408
ns2.oniaas.io. 5 AAAA 2606:4700:5a:0:0:0:ac40:3514
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0