Apex domains cannot have CNAME records.
Question and response
Question
dig nexovirta.com. NS
Answer
nexovirta.com. 4 NS ns-1677.awsdns-17.co.uk.
nexovirta.com. 4 NS ns-1964.awsdns-53.co.uk.
nexovirta.com. 4 NS ns-1056.awsdns-04.org.
nexovirta.com. 4 NS ns-1330.awsdns-38.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0