Apex domains cannot have CNAME records.
Question and response
Question
dig eu-central-1.compute.amazonaws.com. NS
Answer
eu-central-1.compute.amazonaws.com. 5 NS ns-851.awsdns-42.net.
eu-central-1.compute.amazonaws.com. 5 NS ns-478.awsdns-59.com.
eu-central-1.compute.amazonaws.com. 5 NS ns-1733.awsdns-24.co.uk.
eu-central-1.compute.amazonaws.com. 5 NS ns-1467.awsdns-55.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0