Apex domains cannot have CNAME records.
Question and response
Question
dig sfc.wide.ad.jp. NS
Answer
sfc.wide.ad.jp. 3 NS ns1-cns.sfc.wide.ad.jp.
sfc.wide.ad.jp. 3 NS ns.sfc.wide.ad.jp.
sfc.wide.ad.jp. 3 NS ns.fujisawa.wide.ad.jp.
Authority
The response has no authority records.
Additional
ns.sfc.wide.ad.jp. 3 A 203.178.142.143
ns.fujisawa.wide.ad.jp. 1 A 203.178.136.62
ns1-cns.sfc.wide.ad.jp. 3 A 133.27.114.42
ns.sfc.wide.ad.jp. 3 AAAA 2001:200:0:8803:203:178:142:143
ns.fujisawa.wide.ad.jp. 1 AAAA 2001:200:0:1:0:0:0:11
ns1-cns.sfc.wide.ad.jp. 3 AAAA 2001:df2:c900:7f05:0:0:114:42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0