Apex domains cannot have CNAME records.
Question and response
Question
dig ns0.hu. NS
Answer
ns0.hu. 4 NS ns1.e-tiger.net.
ns0.hu. 4 NS ns2.e-tiger.net.
ns0.hu. 4 NS ns3.e-tiger.net.
Authority
The response has no authority records.
Additional
ns1.e-tiger.net. 4 A 193.23.139.1
ns3.e-tiger.net. 4 A 193.23.138.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0