Apex domains cannot have CNAME records.
Question and response
Question
dig dns2.hu. NS
Answer
dns2.hu. 5 NS dns3.hu.
dns2.hu. 5 NS dns1.hu.
dns2.hu. 5 NS sec2.rcode0.net.
dns2.hu. 5 NS dns2.hu.
dns2.hu. 5 NS sec1.rcode0.net.
Authority
The response has no authority records.
Additional
dns1.hu. 5 A 212.52.165.53
dns2.hu. 5 A 194.149.0.68
dns3.hu. 5 A 94.199.49.123
sec1.rcode0.net. 5 A 192.174.68.100
sec2.rcode0.net. 5 A 176.97.158.100
sec1.rcode0.net. 5 AAAA 2001:67c:1bc:0:0:0:0:100
sec2.rcode0.net. 5 AAAA 2001:67c:10b8:0:0:0:0:100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0