mailserver2.cetelem.com.br has no NS records.
NS records for this zone are defined at cetelem.com.br.
NS records for this zone are defined at cetelem.com.br.
Question and response
Question
dig mailserver2.cetelem.com.br. NS
Answer
The response has no answer records.
Authority
cetelem.com.br. 300 SOA ns1.cetelem.com.br. microinformatica.cetelem.com.br. 1202 7200 3600 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0