Apex domains cannot have CNAME records.
Question and response
Question
dig clbgamevn.com. NS
Answer
clbgamevn.com. 5 NS ns1.clbgamevn.com.
clbgamevn.com. 5 NS ns2.clbgamevn.com.
Authority
The response has no authority records.
Additional
ns1.clbgamevn.com. 5 A 51.79.21.217
ns2.clbgamevn.com. 5 A 51.79.117.48
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0