Apex domains cannot have CNAME records.
Question and response
Question
dig elmu.hu. NS
Answer
elmu.hu. 5 NS global1.eondns.net.
elmu.hu. 5 NS global2.eondns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0