Apex domains cannot have CNAME records.
Question and response
Question
dig cloud-sec-av.com. NS
Answer
cloud-sec-av.com. 5 NS ns-1048.awsdns-03.org.
cloud-sec-av.com. 5 NS ns-1969.awsdns-54.co.uk.
cloud-sec-av.com. 5 NS ns-258.awsdns-32.com.
cloud-sec-av.com. 5 NS ns-708.awsdns-24.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0