Apex domains cannot have CNAME records.
Question and response
Question
dig gmcpartstore.com. NS
Answer
gmcpartstore.com. 5 NS ns-174.awsdns-21.com.
gmcpartstore.com. 5 NS ns-72.awsdns-09.com.
gmcpartstore.com. 5 NS ns-169.awsdns-21.com.
gmcpartstore.com. 5 NS ns-1973.awsdns-54.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0