20.0.35.146.210.in-addr.arpa has no NS records.
NS records for this zone are defined at 0.35.146.210.in-addr.arpa.
NS records for this zone are defined at 0.35.146.210.in-addr.arpa.
Question and response
Question
dig 20.0.35.146.210.in-addr.arpa. NS
Answer
The response has no answer records.
Authority
0.35.146.210.in-addr.arpa. 900 SOA ns-w2.mb.softbank.jp. postmaster.mb.softbank.jp. 2015090903 1800 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0