Apex domains cannot have CNAME records.
Question and response
Question
dig ix.fi. NS
Answer
ix.fi. 5 NS ns2.mmd.net.
ix.fi. 5 NS ns.mmd.net.
ix.fi. 5 NS ns3.mmd.net.
Authority
The response has no authority records.
Additional
ns.mmd.net. 5 A 80.83.0.53
ns2.mmd.net. 5 A 80.83.0.54
ns3.mmd.net. 5 A 159.253.30.42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0