Apex domains cannot have CNAME records.
Question and response
Question
dig netforest.ad.jp. NS
Answer
netforest.ad.jp. 2 NS ns2.netforest.ad.jp.
netforest.ad.jp. 2 NS ns3.netforest.ad.jp.
netforest.ad.jp. 2 NS ns1.netforest.ad.jp.
Authority
The response has no authority records.
Additional
ns1.netforest.ad.jp. 2 A 218.45.16.69
ns2.netforest.ad.jp. 2 A 218.45.29.109
ns3.netforest.ad.jp. 2 A 15.168.4.91
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0