mxin2.airnet.ne.jp has no CNAME records.
Question and response
Question
dig mxin2.airnet.ne.jp. NS
Answer
The response has no answer records.
Authority
airnet.ne.jp. 3600 SOA pns.air.ne.jp. support.air.ad.jp. 2026030502 10800 3600 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0