Apex domains cannot have CNAME records.
Question and response
Question
dig dragonet.es. NS
Answer
dragonet.es. 5 NS dns1.dragonet.es.
dragonet.es. 5 NS dns2.dragonet.es.
Authority
The response has no authority records.
Additional
dns1.dragonet.es. 5 A 217.70.240.135
dns2.dragonet.es. 5 A 217.70.240.136
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0