Apex domains cannot have CNAME records.
Question and response
Question
dig auiqqraehs.acm-validations.aws. NS
Answer
auiqqraehs.acm-validations.aws. 5 NS ns-1704.awsdns-21.co.uk.
auiqqraehs.acm-validations.aws. 5 NS ns-1265.awsdns-30.org.
auiqqraehs.acm-validations.aws. 5 NS ns-385.awsdns-48.com.
auiqqraehs.acm-validations.aws. 5 NS ns-609.awsdns-12.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0