Apex domains cannot have CNAME records.
Question and response
Question
dig eonet.ne.jp. NS
Answer
eonet.ne.jp. 2 NS a3-67.akam.net.
eonet.ne.jp. 2 NS a10-65.akam.net.
eonet.ne.jp. 2 NS a18-67.akam.net.
eonet.ne.jp. 2 NS a7-66.akam.net.
eonet.ne.jp. 2 NS ns1.eonet.ne.jp.
eonet.ne.jp. 2 NS a1-232.akam.net.
eonet.ne.jp. 2 NS ns7.eonet.ne.jp.
eonet.ne.jp. 2 NS a22-65.akam.net.
Authority
The response has no authority records.
Additional
ns1.eonet.ne.jp. 2 A 61.122.241.177
ns7.eonet.ne.jp. 2 A 60.56.0.134
a3-67.akam.net. 3 A 96.7.49.67
a7-66.akam.net. 3 A 23.61.199.66
a1-232.akam.net. 3 A 193.108.91.232
a10-65.akam.net. 3 A 96.7.50.65
a18-67.akam.net. 3 A 95.101.36.67
a22-65.akam.net. 3 A 23.211.61.65
ns1.eonet.ne.jp. 3 AAAA 2001:ce8:0:1711:0:0:0:1
ns7.eonet.ne.jp. 3 AAAA 2001:ce8:0:1511:0:0:0:1
a3-67.akam.net. 3 AAAA 2600:1408:1c:0:0:0:0:43
a7-66.akam.net. 3 AAAA 2600:1406:32:0:0:0:0:42
a1-232.akam.net. 3 AAAA 2600:1401:2:0:0:0:0:e8
a10-65.akam.net. 3 AAAA 2600:1480:d000:0:0:0:0:41
a18-67.akam.net. 3 AAAA 2600:1480:4800:0:0:0:0:43
a22-65.akam.net. 3 AAAA 2600:1480:7800:0:0:0:0:41
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0