Mx.castam.com.br has no NS records.
NS records for this zone are defined at castam.com.br.
NS records for this zone are defined at castam.com.br.
Question and response
Question
dig Mx.castam.com.br. NS
Answer
The response has no answer records.
Authority
castam.com.br. 86400 SOA ns978.hostgator.com.br. root.br978.hostgator.com.br. 2026021501 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0