mx2.nr1net.com has no NS records.
NS records for this zone are defined at nr1net.com.
NS records for this zone are defined at nr1net.com.
Question and response
Question
dig mx20.filtermail.eu. NS
Answer
The response has no answer records.
Authority
filtermail.eu. 86400 SOA ns1.sqr.nl. hostmaster.filtermail.eu. 2025042201 3600 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0