Apex domains cannot have CNAME records.
Question and response
Question
dig net.orange.es. NS
Answer
net.orange.es. 5 NS ns1.orange.es.
net.orange.es. 5 NS ns2.orange.es.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0