mails.combrmail.com.br has no NS records.
NS records for this zone are defined at combrmail.com.br.
NS records for this zone are defined at combrmail.com.br.
Question and response
Question
dig mails.combrmail.com.br. NS
Answer
The response has no answer records.
Authority
combrmail.com.br. 1800 SOA justin.ns.cloudflare.com. dns.cloudflare.com. 2397158791 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0