mx.ambisys.net has no NS records.
NS records for this zone are defined at ambisys.net.
NS records for this zone are defined at ambisys.net.
Question and response
Question
dig mx.ambisys.net. NS
Answer
The response has no answer records.
Authority
ambisys.net. 1800 SOA ns0.ambisys.jp. hostmaster.ambisys.com. 2025041401 10800 1800 3600000 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0