Apex domains cannot have CNAME records.
Question and response
Question
dig tribanco.com.br. NS
Answer
tribanco.com.br. 5 NS ns-1628.awsdns-11.co.uk.
tribanco.com.br. 5 NS ns-131.awsdns-16.com.
tribanco.com.br. 5 NS ns-868.awsdns-44.net.
tribanco.com.br. 5 NS ns-1184.awsdns-20.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0