mx.mypetrojobs.com has no NS records.
NS records for this zone are defined at mypetrojobs.com.
NS records for this zone are defined at mypetrojobs.com.
Question and response
Question
dig mx.mypetrojobs.com. NS
Answer
The response has no answer records.
Authority
mypetrojobs.com. 3600 SOA dns.mypetrojobs.com. hostmaster.mypetrojobs.com. 1125920225 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0