dns.mortillo.com has no CNAME records.
Question and response
Question
dig dns.mortillo.com. NS
Answer
The response has no answer records.
Authority
mortillo.com. 2480 SOA dns.mortillo.com. hostmaster.mortillo.com. 1222242044 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0