dns1.mind.ad.jp has no CNAME records.
Question and response
Question
dig dns1.mind.ad.jp. NS
Answer
The response has no answer records.
Authority
mind.ad.jp. 31 SOA ns2.mind.ad.jp. hostmaster.mind.ad.jp. 3000000027 10800 3600 604800 1200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0