Apex domains cannot have CNAME records.
Question and response
Question
dig dns-servicios.es. NS
Answer
dns-servicios.es. 2 NS ns3.dns-servicios.es.
dns-servicios.es. 2 NS ns4.dns-servicios.es.
Authority
The response has no authority records.
Additional
ns3.dns-servicios.es. 2 A 86.109.102.131
ns4.dns-servicios.es. 2 A 176.28.119.196
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0