mailing.contratanet.com.br has no NS records.
NS records for this zone are defined at contratanet.com.br.
NS records for this zone are defined at contratanet.com.br.
Question and response
Question
dig mailing.contratanet.com.br. NS
Answer
The response has no answer records.
Authority
contratanet.com.br. 1800 SOA earl.ns.cloudflare.com. dns.cloudflare.com. 2398775233 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0