mail.mailx.com.br has no NS records.
NS records for this zone are defined at mailx.com.br.
NS records for this zone are defined at mailx.com.br.
Question and response
Question
dig mail.mailx.com.br. NS
Answer
The response has no answer records.
Authority
mailx.com.br. 1800 SOA kim.ns.cloudflare.com. dns.cloudflare.com. 2397722517 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0