mx.maxf.net has no NS records.
NS records for this zone are defined at maxf.net.
NS records for this zone are defined at maxf.net.
Question and response
Question
dig mx.maxf.net. NS
Answer
The response has no answer records.
Authority
maxf.net. 600 SOA maxf.net. dns.maxf.net. 1770158386 600 600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0