mx.scoreperfectgmat.com has no NS records.
NS records for this zone are defined at scoreperfectgmat.com.
NS records for this zone are defined at scoreperfectgmat.com.
Question and response
Question
dig mx.scoreperfectgmat.com. NS
Answer
The response has no answer records.
Authority
The response has no authority records.
Additional
The response has no additional records.