Apex domains cannot have CNAME records.
Question and response
Question
dig adopt-a-grandparent.com. NS
Answer
adopt-a-grandparent.com. 5 NS ns-1725.awsdns-23.co.uk.
adopt-a-grandparent.com. 5 NS ns-1493.awsdns-58.org.
adopt-a-grandparent.com. 5 NS ns-54.awsdns-06.com.
adopt-a-grandparent.com. 5 NS ns-1716.awsdns-22.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0