i2.i.sinet.ad.jp has no CNAME records.
Question and response
Question
dig i2.i.sinet.ad.jp. NS
Answer
The response has no answer records.
Authority
i.sinet.ad.jp. 180 SOA dns01.sinet.ad.jp. postmaster.sinet.ad.jp. 2024011902 30 60 360 180
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0