Apex domains cannot have CNAME records.
Question and response
Question
dig netcomunicaciones.com. NS
Answer
netcomunicaciones.com. 5 NS s.ns34.intelsrv.net.
netcomunicaciones.com. 5 NS s.ns33.intelsrv.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0