Apex domains cannot have CNAME records.
Question and response
Question
dig dox.jp. NS
Answer
dox.jp. 5 NS ns01.iij-dns.jp.
dox.jp. 5 NS ns00.iij-dns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0