Apex domains cannot have CNAME records.
Question and response
Question
dig apifon-mail.com. NS
Answer
apifon-mail.com. 5 NS ns-1312.awsdns-36.org.
apifon-mail.com. 5 NS ns-592.awsdns-10.net.
apifon-mail.com. 5 NS ns-317.awsdns-39.com.
apifon-mail.com. 5 NS ns-1666.awsdns-16.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0