Apex domains cannot have CNAME records.
Question and response
Question
dig vps-13606868.tudoall.com.br. NS
Answer
vps-13606868.tudoall.com.br. 5 NS ns1.162-240-145-136.hostgator-br.com.
vps-13606868.tudoall.com.br. 5 NS ns2.162-240-145-136.hostgator-br.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0