Apex domains cannot have CNAME records.
Question and response
Question
dig adaptavist.com. NS
Answer
adaptavist.com. 5 NS ns-848.awsdns-42.net.
adaptavist.com. 5 NS ns-1976.awsdns-55.co.uk.
adaptavist.com. 5 NS ns-400.awsdns-50.com.
adaptavist.com. 5 NS ns-1313.awsdns-36.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0