Apex domains cannot have CNAME records.
Question and response
Question
dig ckp.jp. NS
Answer
ckp.jp. 4 NS ns3.mcnet.ad.jp.
ckp.jp. 4 NS ns2.ckp.jp.
ckp.jp. 4 NS ns.ckp.jp.
Authority
The response has no authority records.
Additional
ns.ckp.jp. 4 A 210.156.0.130
ns.ckp.jp. 4 AAAA 2001:da0:0:128:0:0:0:130
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0