dns4.fastweb.it has no CNAME records.
Question and response
Question
dig dns4.fastweb.it. NS
Answer
The response has no answer records.
Authority
fastweb.it. 1654 SOA dns3.fastweb.it. dnsmaster.fastweb.it. 2026021000 10800 900 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0