mx.portsit.com has no NS records.
NS records for this zone are defined at portsit.com.
NS records for this zone are defined at portsit.com.
Question and response
Question
dig mx.portsit.com. NS
Answer
The response has no answer records.
Authority
portsit.com. 3600 SOA dns01.dipcon.com. registry.ports.net. 2026021500 1800 900 1814400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0