iagau.onmicrosoft.com has no NS records.
NS records for this zone are defined at onmicrosoft.com.
NS records for this zone are defined at onmicrosoft.com.
Question and response
Question
dig iagau.onmicrosoft.com. NS
Answer
The response has no answer records.
Authority
onmicrosoft.com. 300 SOA ns1-208.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 3600 300 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0