ns.thnic.net has no CNAME records.
Question and response
Question
dig ns.thnic.net. NS
Answer
The response has no answer records.
Authority
thnic.net. 3600 SOA ns-a.thnic.co.th. registry.thains.co.th. 2026030401 1800 1800 864000 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0