Apex domains cannot have CNAME records.
Question and response
Question
dig djqtsrsxkq.acm-validations.aws. NS
Answer
djqtsrsxkq.acm-validations.aws. 5 NS ns-636.awsdns-15.net.
djqtsrsxkq.acm-validations.aws. 5 NS ns-447.awsdns-55.com.
djqtsrsxkq.acm-validations.aws. 5 NS ns-1819.awsdns-35.co.uk.
djqtsrsxkq.acm-validations.aws. 5 NS ns-1289.awsdns-33.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0