Apex domains cannot have CNAME records.
Question and response
Question
dig ltfvzjuylp.acm-validations.aws. NS
Answer
ltfvzjuylp.acm-validations.aws. 4 NS ns-84.awsdns-10.com.
ltfvzjuylp.acm-validations.aws. 4 NS ns-2005.awsdns-58.co.uk.
ltfvzjuylp.acm-validations.aws. 4 NS ns-1124.awsdns-12.org.
ltfvzjuylp.acm-validations.aws. 4 NS ns-842.awsdns-41.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0