Apex domains cannot have CNAME records.
Question and response
Question
dig zts.hu. NS
Answer
zts.hu. 1 NS edna.ns.cloudflare.com.
zts.hu. 1 NS plato.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
edna.ns.cloudflare.com. 2 A 108.162.192.109
edna.ns.cloudflare.com. 2 A 172.64.32.109
edna.ns.cloudflare.com. 2 A 173.245.58.109
plato.ns.cloudflare.com. 2 A 108.162.193.223
plato.ns.cloudflare.com. 2 A 172.64.33.223
plato.ns.cloudflare.com. 2 A 173.245.59.223
edna.ns.cloudflare.com. 2 AAAA 2606:4700:50:0:0:0:adf5:3a6d
edna.ns.cloudflare.com. 2 AAAA 2803:f800:50:0:0:0:6ca2:c06d
edna.ns.cloudflare.com. 2 AAAA 2a06:98c1:50:0:0:0:ac40:206d
plato.ns.cloudflare.com. 2 AAAA 2606:4700:58:0:0:0:adf5:3bdf
plato.ns.cloudflare.com. 2 AAAA 2803:f800:50:0:0:0:6ca2:c1df
plato.ns.cloudflare.com. 2 AAAA 2a06:98c1:50:0:0:0:ac40:21df
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0