206.238.19.71.in-addr.arpa has no NS records.
NS records for this zone are defined at 238.19.71.in-addr.arpa.
NS records for this zone are defined at 238.19.71.in-addr.arpa.
Question and response
Question
dig 206.238.19.71.in-addr.arpa. NS
Answer
The response has no answer records.
Authority
238.19.71.in-addr.arpa. 3600 SOA ns1.birdhosting.com. staff.innoscale.net. 2017051303 3600 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0