Apex domains cannot have CNAME records.
Question and response
Question
dig RIPN.net. NS
Answer
RIPN.net. 5 NS b.dns.RIPN.net.
RIPN.net. 5 NS e.dns.RIPN.net.
RIPN.net. 5 NS f.dns.RIPN.net.
RIPN.net. 5 NS a.dns.RIPN.net.
RIPN.net. 5 NS d.dns.RIPN.net.
Authority
The response has no authority records.
Additional
a.dns.ripn.net. 5 A 193.232.128.6
b.dns.ripn.net. 5 A 194.85.252.62
d.dns.ripn.net. 5 A 194.190.124.17
e.dns.ripn.net. 5 A 193.232.142.17
f.dns.ripn.net. 5 A 193.232.156.17
a.dns.ripn.net. 5 AAAA 2001:678:17:0:193:232:128:6
b.dns.ripn.net. 5 AAAA 2001:678:16:0:194:85:252:62
d.dns.ripn.net. 5 AAAA 2001:678:18:0:194:190:124:17
e.dns.ripn.net. 5 AAAA 2001:678:15:0:193:232:142:17
f.dns.ripn.net. 5 AAAA 2001:678:14:0:193:232:156:17
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0