Apex domains cannot have CNAME records.
Question and response
Question
dig euronetrt.hu. NS
Answer
euronetrt.hu. 5 NS ns2.euronetrt.hu.
euronetrt.hu. 5 NS nova.euronetrt.hu.
euronetrt.hu. 5 NS ns2.dravanet.hu.
Authority
The response has no authority records.
Additional
ns2.dravanet.hu. 5 A 109.61.11.24
nova.euronetrt.hu. 5 A 109.61.9.67
ns2.dravanet.hu. 5 AAAA 2a01:be00:0:b:35:0:b:18
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0