mx.marin.ad has no NS records.
NS records for this zone are defined at marin.ad.
NS records for this zone are defined at marin.ad.
Question and response
Question
dig mx.marin.ad. NS
Answer
The response has no answer records.
Authority
marin.ad. 3600 SOA pns61.cloudns.net. support.cloudns.net. 2026010101 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0