Apex domains cannot have CNAME records.
Question and response
Question
dig harperdbcloud.com. NS
Answer
harperdbcloud.com. 4 NS ns-1860.awsdns-40.co.uk.
harperdbcloud.com. 4 NS ns-257.awsdns-32.com.
harperdbcloud.com. 4 NS ns-777.awsdns-33.net.
harperdbcloud.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