Apex domains cannot have CNAME records.
Question and response
Question
dig gradesfirst.com. NS
Answer
gradesfirst.com. 4 NS ns-602.awsdns-11.net.
gradesfirst.com. 4 NS ns-163.awsdns-20.com.
gradesfirst.com. 4 NS ns-1801.awsdns-33.co.uk.
gradesfirst.com. 4 NS ns-1469.awsdns-55.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0