dmail02.kagoya.net has no CNAME records.
Question and response
Question
dig dmail02.kagoya.net. NS
Answer
The response has no answer records.
Authority
kagoya.net. 600 SOA ns.kagoya.net. root.kagoya.net. 2026030700 3900 300 360000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0