129.128.51.121.27.in-addr.arpa has no NS records.
NS records for this zone are defined at 128.51.121.27.in-addr.arpa.
NS records for this zone are defined at 128.51.121.27.in-addr.arpa.
Question and response
Question
dig 129.128.51.121.27.in-addr.arpa. NS
Answer
The response has no answer records.
Authority
128.51.121.27.in-addr.arpa. 900 SOA dns1.broadline.ne.jp. dns-info.broadline.ne.jp. 67 10800 900 604800 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0