Apex domains cannot have CNAME records.
Question and response
Question
dig azdentalschool.com. NS
Answer
azdentalschool.com. 5 NS ns1.azdentalschool.com.
azdentalschool.com. 5 NS ns2.azdentalschool.com.
Authority
The response has no authority records.
Additional
ns1.azdentalschool.com. 5 A 86.111.188.134
ns2.azdentalschool.com. 5 A 51.38.144.212
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0