Apex domains cannot have CNAME records.
Question and response
Question
dig hadcloudservers.com.br. NS
Answer
hadcloudservers.com.br. 5 NS cloud-dns01.hadcloud.srv.br.
hadcloudservers.com.br. 5 NS cloud-dns02.hadcloud.srv.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0