pecbackup.pec.ad.aruba.it has no CNAME records.
Question and response
Question
dig pecbackup.pec.ad.aruba.it. NS
Answer
The response has no answer records.
Authority
pec.ad.aruba.it. 3600 SOA dc1.ad.aruba.it. hostmaster.ad.aruba.it. 38406 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0