Apex domains cannot have CNAME records.
Question and response
Question
dig isiscom.hu. NS
Answer
isiscom.hu. 5 NS ns1.elender.hu.
isiscom.hu. 5 NS ns.isis-com.hu.
Authority
The response has no authority records.
Additional
ns.isis-com.hu. 5 A 77.221.39.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0