Apex domains cannot have CNAME records.
Question and response
Question
dig checksafetyfirst.org. NS
Answer
checksafetyfirst.org. 5 NS ns-1854.awsdns-39.co.uk.
checksafetyfirst.org. 5 NS ns-54.awsdns-06.com.
checksafetyfirst.org. 5 NS ns-79.awsdns-09.com.
checksafetyfirst.org. 5 NS ns-406.awsdns-50.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0