mx.mirohost.net has no NS records.
NS records for this zone are defined at mirohost.net.
NS records for this zone are defined at mirohost.net.
Question and response
Question
dig mx.mirohost.net. NS
Answer
The response has no answer records.
Authority
mirohost.net. 900 SOA nsa2.srv53.net. support.dnshosting.org. 1771684424 1800 600 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0