o1.ptr3816.codetwo.com has no NS records.
NS records for this zone are defined at codetwo.com.
NS records for this zone are defined at codetwo.com.
Question and response
Question
dig o1.ptr3816.codetwo.com. NS
Answer
The response has no answer records.
Authority
codetwo.com. 180 SOA ns10.digicertdns.com. dns.digicertdns.com. 2009010523 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0