mx.nethost.info has no NS records.
NS records for this zone are defined at nethost.info.
NS records for this zone are defined at nethost.info.
Question and response
Question
dig mx.nethost.info. NS
Answer
The response has no answer records.
Authority
nethost.info. 3600 SOA dns.nethost.info. hostmaster.nethost.info. 1795186756 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0