mail.virtuaserver.com.br has no NS records.
NS records for this zone are defined at virtuaserver.com.br.
NS records for this zone are defined at virtuaserver.com.br.
Question and response
Question
dig mail.virtuaserver.com.br. NS
Answer
The response has no answer records.
Authority
virtuaserver.com.br. 39600 SOA ns.virtuaserver.com.br. root.virtuaserver.com.br. 1772572722 28800 7200 604800 39600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0