Apex domains cannot have CNAME records.
Question and response
Question
dig exfort.net. NS
Answer
exfort.net. 5 NS ns6.via.or.jp.
exfort.net. 5 NS ns6.intervia.ad.jp.
Authority
The response has no authority records.
Additional
ns6.via.or.jp. 5 A 203.182.20.46
ns6.intervia.ad.jp. 5 A 203.182.20.14
ns6.via.or.jp. 5 AAAA 2001:c80:0:1001:0:0:0:a
ns6.intervia.ad.jp. 5 AAAA 2001:c80:0:1000:0:0:0:a
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0