mx01.wien.gv.at has no NS records.
NS records for this zone are defined at wien.gv.at.
NS records for this zone are defined at wien.gv.at.
Question and response
Question
dig mx01.wien.gv.at. NS
Answer
The response has no answer records.
Authority
wien.gv.at. 10800 SOA ns1.wien.at. hostmaster.magwien.gv.at. 1773722402 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0