mail3.cvc.com.br has no NS records.
NS records for this zone are defined at cvc.com.br.
NS records for this zone are defined at cvc.com.br.
Question and response
Question
dig mail3.cvc.com.br. NS
Answer
The response has no answer records.
Authority
cvc.com.br. 300 SOA ns1.p201.dns.oraclecloud.net. hostmaster.cvc.com.br. 150 3600 600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0