ns4.udns.com.br has no NS records.
NS records for this zone are defined at udns.com.br.
NS records for this zone are defined at udns.com.br.
Question and response
Question
dig ns4.udns.com.br. NS
Answer
The response has no answer records.
Authority
udns.com.br. 3600 SOA ns1.udns.com.br. noc.udns.com.br. 2025091701 10800 900 604800 86400
Additional
. 0 OPT [{Extended_DNS_Error: PROHIBITED}] ; payload 1232, xrcode 0, version 0, flags 0