ns.kagoya.net has no MX records.
Question and response
Question
dig ns.kagoya.net. MX
Answer
The response has no answer records.
Authority
kagoya.net. 600 SOA ns.kagoya.net. root.kagoya.net. 2026022200 3900 300 360000 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0