mailserver1.ampernet.com.br has no NS records.
NS records for this zone are defined at ampernet.com.br.
NS records for this zone are defined at ampernet.com.br.
Question and response
Question
dig mailserver1.ampernet.com.br. NS
Answer
The response has no answer records.
Authority
ampernet.com.br. 3600 SOA ns1.ampernet.com.br. postmaster.ampernet.com.br. 2025102805 3600 3600 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0