Apex domains cannot have CNAME records.
Question and response
Question
dig heikkiutula.com. NS
Answer
heikkiutula.com. 5 NS ns-1380.awsdns-44.org.
heikkiutula.com. 5 NS ns-1062.awsdns-04.org.
heikkiutula.com. 5 NS ns-220.awsdns-27.com.
heikkiutula.com. 5 NS ns-1848.awsdns-39.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0