mailhost.myvan.descartes.com has no NS records.
NS records for this zone are defined at myvan.descartes.com.
NS records for this zone are defined at myvan.descartes.com.
Question and response
Question
dig mailhost.myvan.descartes.com. NS
Answer
The response has no answer records.
Authority
myvan.descartes.com. 900 SOA ns-1304.awsdns-35.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0