Apex domains cannot have CNAME records.
Question and response
Question
dig brs.com.br. NS
Answer
brs.com.br. 2 NS ns2.brs.com.br.
brs.com.br. 2 NS ns1.brs.com.br.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0