Apex domains cannot have CNAME records.
Question and response
Question
dig zyxoventra.com. NS
Answer
zyxoventra.com. 4 NS ns-420.awsdns-52.com.
zyxoventra.com. 4 NS ns-1640.awsdns-13.co.uk.
zyxoventra.com. 4 NS ns-1699.awsdns-20.co.uk.
zyxoventra.com. 4 NS ns-1.awsdns-00.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0