mail.koh-kae.com has no CNAME records.
Question and response
Question
dig mail.koh-kae.com. NS
Answer
The response has no answer records.
Authority
koh-kae.com. 3600 SOA win-alfftollgm4. hostmaster. 97 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0