ns.telefonica-ca.net has no CNAME records.
Question and response
Question
dig ns.telefonica-ca.net. NS
Answer
The response has no answer records.
Authority
telefonica-ca.net. 6138 SOA ns1.dominioabsoluto.com. hostmaster.ns1.dominioabsoluto.com. 1772603245 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0