Apex domains cannot have CNAME records.
Question and response
Question
dig funet.fi. NS
Answer
funet.fi. 5 NS ns1.z.fi.
funet.fi. 5 NS ns-secondary.funet.fi.
funet.fi. 5 NS ns.funet.fi.
funet.fi. 5 NS ns2.z.fi.
funet.fi. 5 NS ns2.funet.fi.
Authority
The response has no authority records.
Additional
ns.funet.fi. 5 A 128.214.46.64
ns2.funet.fi. 5 A 128.214.46.66
ns-secondary.funet.fi. 5 A 128.214.248.132
ns.funet.fi. 5 AAAA 2001:708:10:54:0:0:0:53
ns2.funet.fi. 5 AAAA 2001:708:0:0:0:0:53:66
ns-secondary.funet.fi. 5 AAAA 2001:708:10:55:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0