mail.diusframi.es has no CNAME records.
Question and response
Question
dig mail.diusframi.es. NS
Answer
The response has no answer records.
Authority
diusframi.es. 300 SOA dns1.nominalia.com. root.dns1.nominalia.com. 1766144925 86400 7200 2592000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0