Merge pull request #217133 from amolbms/update-online-endpoint-troubleshoot-guide

Update online endpoint troubleshoot guide

Author: prmerger-automator[bot]

includes/machine-learning-online-endpoint-troubleshooting.md

@@ -69,6 +69,17 @@ If the value of `bypass` isn't `AzureServices`, use the guidance in the [Configu
 
     The results should contain an entry that is similar to `*.<GUID>.inference.<region>`.
 1. If no inference value is returned, delete the private endpoint for the workspace and then recreate it. For more information, see [How to configure a private endpoint](../articles/container-registry/container-registry-private-link.md). 
+1. If the workspace with a private endpoint is setup using a custom DNS [How to use your workspace with a custom DNS server](../articles/machine-learning/how-to-custom-dns.md), use following command to verify if resolution works correctly from custom DNS. 
+    ```bash
+    dig endpointname.westcentralus.inference.ml.azure.com
+    ```
+    
+    If this fails to resolve to A record, verify if the resolution works from Azure DNS(168.63.129.16). 
+    ```bash
+    dig @168.63.129.16 endpointname.westcentralus.inference.ml.azure.com
+    ```
+
+    if this succeeds then troubleshoot conditional forwarder for private link on custom DNS.
 
 ### Online deployments can't be scored