sip.dotarai.co.th has no CNAME records.
Question and response
Question
dig sip.dotarai.co.th. NS
Answer
The response has no answer records.
Authority
dotarai.co.th. 3600 SOA ns.mail.in.th. hostmaster\.mail.in.th. 2026022627 86400 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0