3.43.233.68.in-addr.arpa has no NS records.
NS records for this zone are defined at 43.233.68.in-addr.arpa.
NS records for this zone are defined at 43.233.68.in-addr.arpa.
Question and response
Question
dig 3.43.233.68.in-addr.arpa. NS
Answer
The response has no answer records.
Authority
43.233.68.in-addr.arpa. 86400 SOA pns.hostcolor.net. hostmaster.hostcolor.com. 2013053101 10800 900 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0