Apex domains cannot have CNAME records.
Question and response
Question
dig netbrasil.app.br. NS
Answer
netbrasil.app.br. 1 NS ns2.netbrasil.app.br.
netbrasil.app.br. 1 NS ns1.netbrasil.app.br.
Authority
The response has no authority records.
Additional
ns1.netbrasil.app.br. 1 A 131.161.216.86
ns2.netbrasil.app.br. 1 A 131.161.216.90
ns1.netbrasil.app.br. 1 AAAA 2804:1dc8:f800:9:0:0:0:2
ns2.netbrasil.app.br. 1 AAAA 2804:1dc8:f800:10:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0