Apex domains cannot have CNAME records.
Question and response
Question
dig exabit.hu. NS
Answer
exabit.hu. 4 NS ns0.grin.hu.
exabit.hu. 4 NS ns.is.hu.
exabit.hu. 4 NS ns.tolna.net.
Authority
The response has no authority records.
Additional
ns.tolna.net. 4 A 91.146.167.221
ns.tolna.net. 4 AAAA 2a01:5d0:0:2:0:0:0:3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0