Apex domains cannot have CNAME records.
Question and response
Question
dig pool85-62-117.static.orange.es. NS
Answer
pool85-62-117.static.orange.es. 5 NS dnsa01m-men4.net.orange.es.
pool85-62-117.static.orange.es. 5 NS dnsa01m-jca4.net.orange.es.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0