mail777.byseven.com.br has no NS records.
NS records for this zone are defined at byseven.com.br.
NS records for this zone are defined at byseven.com.br.
Question and response
Question
dig mail777.byseven.com.br. NS
Answer
The response has no answer records.
Authority
byseven.com.br. 300 SOA ns1-07.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 300 300 300 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0