Apex domains cannot have CNAME records.
Question and response
Question
dig zapproved.com. NS
Answer
zapproved.com. 5 NS ns-492.awsdns-61.com.
zapproved.com. 5 NS ns-1318.awsdns-36.org.
zapproved.com. 5 NS ns-596.awsdns-10.net.
zapproved.com. 5 NS ns-1737.awsdns-25.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0