smtp.virtua.com.br has no NS records.
NS records for this zone are defined at virtua.com.br.
NS records for this zone are defined at virtua.com.br.
Question and response
Question
dig smtp.virtua.com.br. NS
Answer
The response has no answer records.
Authority
virtua.com.br. 300 SOA root.virtua.com.br. postmaster.virtua.com.br. 2026030402 300 300 86400 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0