sng1smtp2.skytap.com has no NS records.
NS records for this zone are defined at skytap.com.
NS records for this zone are defined at skytap.com.
Question and response
Question
dig sng1smtp2.skytap.com. NS
Answer
The response has no answer records.
Authority
skytap.com. 900 SOA ns-1405.awsdns-47.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0