Apex domains cannot have CNAME records.
Question and response
Question
dig spamexperts.com. NS
Answer
spamexperts.com. 5 NS ns-1612.awsdns-09.co.uk.
spamexperts.com. 5 NS ns-1092.awsdns-08.org.
spamexperts.com. 5 NS ns-146.awsdns-18.com.
spamexperts.com. 5 NS ns-961.awsdns-56.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0