Apex domains cannot have CNAME records.
Question and response
Question
dig hdsnet.hu. NS
Answer
hdsnet.hu. 3 NS ns1.hdsnet.hu.
hdsnet.hu. 3 NS ns2.digi.hu.
Authority
The response has no authority records.
Additional
ns1.hdsnet.hu. 3 A 193.110.56.1
ns2.digi.hu. 3 A 92.249.129.105
ns1.hdsnet.hu. 3 AAAA 2a01:368:a:0:0:0:0:11
ns2.digi.hu. 3 AAAA 2a01:368:a:0:0:0:0:12
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0