mx3.bol.com.br has no NS records.
NS records for this zone are defined at bol.com.br.
NS records for this zone are defined at bol.com.br.
Question and response
Question
dig mx3.bol.com.br. NS
Answer
The response has no answer records.
Authority
bol.com.br. 900 SOA a10-dns-uolcsfe1.host.intranet. nsmaster.bol.com.br. 463 3600 1800 432000 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0