Apex domains cannot have CNAME records.
Question and response
Question
dig shi.kvh.ne.jp. NS
Answer
shi.kvh.ne.jp. 5 NS nameserver1.kvh.ne.jp.
shi.kvh.ne.jp. 5 NS nameserver2.kvh.ne.jp.
Authority
The response has no authority records.
Additional
nameserver1.kvh.ne.jp. 5 A 61.120.195.101
nameserver2.kvh.ne.jp. 5 A 203.167.44.101
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0