mx.subsys.no has no NS records.
NS records for this zone are defined at subsys.no.
NS records for this zone are defined at subsys.no.
Question and response
Question
dig mx.subsys.no. NS
Answer
The response has no answer records.
Authority
subsys.no. 300 SOA ns1.subsys.no. hostmaster.subsys.no. 1771043141 300 75 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0