Apex domains cannot have CNAME records.
Question and response
Question
dig cableworld.es. NS
Answer
cableworld.es. 5 NS dns.cableworld.tv.
cableworld.es. 5 NS dns2.cableworld.tv.
cableworld.es. 5 NS dns3.cableworld.tv.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0