outbound.formstack.com has no NS records.
NS records for this zone are defined at formstack.com.
NS records for this zone are defined at formstack.com.
Question and response
Question
dig outbound.formstack.com. NS
Answer
The response has no answer records.
Authority
formstack.com. 900 SOA ns-1400.awsdns-47.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0