smtp-us.letsignit.com has no NS records.
NS records for this zone are defined at letsignit.com.
NS records for this zone are defined at letsignit.com.
Question and response
Question
dig prod-smtp-use-002.eastus.cloudapp.azure.com. NS
Answer
The response has no answer records.
Authority
eastus.cloudapp.azure.com. 60 SOA ns1-201.azure-dns.com. msnhst.microsoft.com. 10001 900 300 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0