ns3.it.com has no NS records.
NS records for this zone are defined at it.com.
NS records for this zone are defined at it.com.
Question and response
Question
dig ns3.it.com. NS
Answer
The response has no answer records.
Authority
it.com. 1800 SOA ns1.it.com. dns.cloudflare.com. 2397997421 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0