Apex domains cannot have CNAME records.
Question and response
Question
dig dnadns.fi. NS
Answer
dnadns.fi. 5 NS ns2.z.fi.
dnadns.fi. 5 NS ns1.z.fi.
dnadns.fi. 5 NS ns3.dnaip.fi.
dnadns.fi. 5 NS ns1.fv.fi.
dnadns.fi. 5 NS ns2.kv9.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0