membership.khai.co.kr has no NS records.
NS records for this zone are defined at co.kr.
NS records for this zone are defined at co.kr.
Question and response
Question
dig membership.khai.co.kr. NS
Answer
The response has no answer records.
Authority
co.kr. 900 SOA g.dns.kr. domain-manager.nic.or.kr. 2603250695 3600 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0