wawd.mx.e.sparkpost.com has no NS records.
NS records for this zone are defined at mx.e.sparkpost.com.
NS records for this zone are defined at mx.e.sparkpost.com.
Question and response
Question
dig wawd.mx.e.sparkpost.com. NS
Answer
The response has no answer records.
Authority
mx.e.sparkpost.com. 900 SOA ns-93.awsdns-11.com. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0