mailopt.algartecnologia.com.br has no NS records.
NS records for this zone are defined at algartecnologia.com.br.
NS records for this zone are defined at algartecnologia.com.br.
Question and response
Question
dig mailopt.algartecnologia.com.br. NS
Answer
The response has no answer records.
Authority
algartecnologia.com.br. 900 SOA ns-39.awsdns-04.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0