mx.postdocrecruiting.com has no NS records.
NS records for this zone are defined at postdocrecruiting.com.
NS records for this zone are defined at postdocrecruiting.com.
Question and response
Question
dig mx.postdocrecruiting.com. NS
Answer
The response has no answer records.
Authority
postdocrecruiting.com. 3600 SOA dns.postdocrecruiting.com. hostmaster.postdocrecruiting.com. 1797737867 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0