Apex domains cannot have CNAME records.
Question and response
Question
dig eu-central-1.amazonses.com. NS
Answer
eu-central-1.amazonses.com. 5 NS ns-974.awsdns-57.net.
eu-central-1.amazonses.com. 5 NS ns-202.awsdns-25.com.
eu-central-1.amazonses.com. 5 NS ns-1920.awsdns-48.co.uk.
eu-central-1.amazonses.com. 5 NS ns-1297.awsdns-34.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0