Apex domains cannot have CNAME records.
Question and response
Question
dig isota.io. NS
Answer
isota.io. 5 NS ns1.isota.io.
isota.io. 5 NS ns2.isota.io.
Authority
The response has no authority records.
Additional
ns1.isota.io. 5 A 94.237.11.31
ns2.isota.io. 5 A 94.237.113.20
ns1.isota.io. 5 AAAA 2a04:3545:1000:720:b055:ddff:fe46:1277
ns2.isota.io. 5 AAAA 2a04:3540:1000:310:b055:ddff:fe46:d49
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0