mail.duasekawan.com has no CNAME records.
Question and response
Question
dig mail.duasekawan.com. NS
Answer
The response has no answer records.
Authority
duasekawan.com. 10800 SOA ns1.dutaint.com. hostmaster.dutaservisindo.co.id. 2021102101 86400 3600 1209600 259200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0