mx2.com4datacenter.com.br has no NS records.
NS records for this zone are defined at com4datacenter.com.br.
NS records for this zone are defined at com4datacenter.com.br.
Question and response
Question
dig mx2.com4datacenter.com.br. NS
Answer
The response has no answer records.
Authority
com4datacenter.com.br. 3600 SOA dns1.com4.com.br. hostmaster.com4.com.br. 291 900 600 86400 3600
Additional
. 0 OPT ; payload 4000, xrcode 0, version 0, flags 0