dns4.istweb.com.br has no NS records.
NS records for this zone are defined at istweb.com.br.
NS records for this zone are defined at istweb.com.br.
Question and response
Question
dig dns4.istweb.com.br. NS
Answer
The response has no answer records.
Authority
istweb.com.br. 86400 SOA ns280.hostgator.com.br. root.br280.hostgator.com.br. 2026013101 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0