Apex domains cannot have CNAME records.
Question and response
Question
dig comunicadoimportante.com.br. NS
Answer
comunicadoimportante.com.br. 5 NS ns12.abovedomains.com.
comunicadoimportante.com.br. 5 NS ns11.abovedomains.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0