dmail01.kagoya.net has no CNAME records.
Question and response
Question
dig dmail01.kagoya.net. NS
Answer
The response has no answer records.
Authority
kagoya.net. 600 SOA ns.kagoya.net. root.kagoya.net. 2026030900 3900 300 360000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0