mx4.fastwebnet.it has no CNAME records.
Question and response
Question
dig mx4.fastwebnet.it. NS
Answer
The response has no answer records.
Authority
fastwebnet.it. 4988 SOA dns3.fastweb.it. dnsmaster.fastweb.it. 2025111101 10800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0