Apex domains cannot have CNAME records.
Question and response
Question
dig elestio.app. NS
Answer
elestio.app. 5 NS ns-52.awsdns-06.com.
elestio.app. 5 NS ns-1460.awsdns-54.org.
elestio.app. 5 NS ns-704.awsdns-24.net.
elestio.app. 5 NS ns-1661.awsdns-15.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0