Apex domains cannot have CNAME records.
Question and response
Question
dig wmqxbylrnj.acm-validations.aws. NS
Answer
wmqxbylrnj.acm-validations.aws. 5 NS ns-1404.awsdns-47.org.
wmqxbylrnj.acm-validations.aws. 5 NS ns-424.awsdns-53.com.
wmqxbylrnj.acm-validations.aws. 5 NS ns-556.awsdns-05.net.
wmqxbylrnj.acm-validations.aws. 5 NS ns-1831.awsdns-36.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0