mx.fillfound.com has no NS records.
NS records for this zone are defined at fillfound.com.
NS records for this zone are defined at fillfound.com.
Question and response
Question
dig mx.fillfound.com. NS
Answer
The response has no answer records.
Authority
fillfound.com. 3600 SOA dns.fillfound.com. hostmaster.fillfound.com. 1458192448 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0