Apex domains cannot have CNAME records.
Question and response
Question
dig grantsnm.com. NS
Answer
grantsnm.com. 5 NS ns-1943.awsdns-50.co.uk.
grantsnm.com. 5 NS ns-192.awsdns-24.com.
grantsnm.com. 5 NS ns-680.awsdns-21.net.
grantsnm.com. 5 NS ns-1607.awsdns-08.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0