Apex domains cannot have CNAME records.
Question and response
Question
dig rrgst.com. NS
Answer
rrgst.com. 5 NS ns2.rrgst.com.
rrgst.com. 5 NS ns1.rrgst.com.
Authority
The response has no authority records.
Additional
ns1.rrgst.com. 5 A 66.181.45.163
ns2.rrgst.com. 5 A 170.130.79.99
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0