6.0.247.55.195.in-addr.arpa has no NS records.
NS records for this zone are defined at 0.247.55.195.in-addr.arpa.
NS records for this zone are defined at 0.247.55.195.in-addr.arpa.
Question and response
Question
dig 6.0.247.55.195.in-addr.arpa. NS
Answer
The response has no answer records.
Authority
0.247.55.195.in-addr.arpa. 86400 SOA minerva.ttd.net. hostmaster.ttd.net. 2015042337 86400 7200 2592000 172800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0