Apex domains cannot have CNAME records.
Question and response
Question
dig inovaiptelecom.com.br. NS
Answer
inovaiptelecom.com.br. 5 NS so2.acquahost.com.br.
inovaiptelecom.com.br. 5 NS so1.acquahost.com.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0