Apex domains cannot have CNAME records.
Question and response
Question
dig kdc.dnp.ad.jp. NS
Answer
kdc.dnp.ad.jp. 5 NS ns001-a7ac8dv51nmgh827.a.d-53.jp.
kdc.dnp.ad.jp. 5 NS ns001-a7ac8dv51nmgh827.a.d-53.net.
kdc.dnp.ad.jp. 5 NS ns001-a7ac8dv51nmgh827.a.d-53.info.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0