The registry (Registro.br) requires that nameservers be properly preconfigured before delegating the domain. This rule applies to both domain registrations and domain updates replacing name servers.
Technical name server requirements
For COM.BR domains, the presence of the SOA record and NS records will suffice, to be considered properly preconfigured. However, the full list of types of error messages can be found at:
https://registro.br/ajuda/gerenciamento-de-conta/mensagem-de-erro/
Registry-Based Check
The registry provides a web-based tool to check the DNS setup for a domain, in Brazilian Portuguese. The test shows whether there are setup errors for one or more nameservers:
https://registro.br/tecnologia/ferramentas/verificacao-de-dns/
Internal Check
You can also check the name servers with the CheckDNS command. For example:
command=checkdns
domain=example.com.br
nameserver0=ns1.nameserver.com
nameserver1=ns2.othernameserver.com