Apex domains cannot have CNAME records.
Question and response
Question
dig movistar-sv.net. NS
Answer
movistar-sv.net. 5 NS ns20.domaincontrol.com.
movistar-sv.net. 5 NS ns19.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0