Apex domains cannot have CNAME records.
Question and response
Question
dig spamexperts.eu. NS
Answer
spamexperts.eu. 5 NS ns-310.awsdns-38.com.
spamexperts.eu. 5 NS ns-1499.awsdns-59.org.
spamexperts.eu. 5 NS ns-968.awsdns-57.net.
spamexperts.eu. 5 NS ns-1682.awsdns-18.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0