dns2.com4.com.br has no NS records.
NS records for this zone are defined at com4.com.br.
NS records for this zone are defined at com4.com.br.
Question and response
Question
dig dns2.com4.com.br. NS
Answer
The response has no answer records.
Authority
com4.com.br. 3600 SOA dns1.com4.com.br. admindominio.com4.com.br. 8241 86400 7200 3600000 7200
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0