Apex domains cannot have CNAME records.
Question and response
Question
dig acoptina.com. NS
Answer
acoptina.com. 4 NS ns-1618.awsdns-10.co.uk.
acoptina.com. 4 NS ns-165.awsdns-20.com.
acoptina.com. 4 NS ns-913.awsdns-50.net.
acoptina.com. 4 NS ns-1379.awsdns-44.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0