Apex domains cannot have CNAME records.
Question and response
Question
dig ihh.jp. NS
Answer
ihh.jp. 4 NS ns1.gao.ne.jp.
ihh.jp. 4 NS ns2.gao.ne.jp.
Authority
The response has no authority records.
Additional
ns1.gao.ne.jp. 4 A 203.133.238.124
ns2.gao.ne.jp. 4 A 210.171.0.127
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0