Apex domains cannot have CNAME records.
Question and response
Question
dig pwd.ne.jp. NS
Answer
pwd.ne.jp. 5 NS temae5.int-gw.kddi.ne.jp.
pwd.ne.jp. 5 NS tegami2.int-gw.kddi.ne.jp.
pwd.ne.jp. 5 NS tegami1.int-gw.kddi.ne.jp.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0