mail1.jib.co.th has no NS records.
NS records for this zone are defined at jib.co.th.
NS records for this zone are defined at jib.co.th.
Question and response
Question
dig mail1.jib.co.th. NS
Answer
The response has no answer records.
Authority
jib.co.th. 1800 SOA pola.ns.cloudflare.com. dns.cloudflare.com. 2397636075 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0