mx.wipi.com.br has no NS records.
NS records for this zone are defined at wipi.com.br.
NS records for this zone are defined at wipi.com.br.
Question and response
Question
dig mx.wipi.com.br. NS
Answer
The response has no answer records.
Authority
wipi.com.br. 86400 SOA ns1.wipi.com.br. admin.wipi.com.br. 2025123102 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0