Apex domains cannot have CNAME records.
Question and response
Question
dig smax3.org. NS
Answer
smax3.org. 5 NS ns-1621.awsdns-10.co.uk.
smax3.org. 5 NS ns-1636.awsdns-12.co.uk.
smax3.org. 5 NS ns-352.awsdns-44.com.
smax3.org. 5 NS ns-1519.awsdns-61.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0