ptr2.sumicity.net.br has no NS records.
NS records for this zone are defined at sumicity.net.br.
NS records for this zone are defined at sumicity.net.br.
Question and response
Question
dig ptr2.sumicity.net.br. NS
Answer
The response has no answer records.
Authority
sumicity.net.br. 300 SOA ns-cloud-c1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0