Update how-to-custom-dns.md

added models DNS required

Author: meerakurup

articles/machine-learning/how-to-custom-dns.md

@@ -166,6 +166,7 @@ The following FQDNs are for Microsoft Azure operated by 21Vianet regions:
 
 * `<instance-name>-22.<region>.instances.azureml.cn` - Only used by the `az ml compute connect-ssh` command to connect to computes in a private virtual network. Not needed if you aren't using a managed network or SSH connections.
 * `<managed online endpoint name>.<region>.inference.ml.azure.cn` - Used by managed online endpoints
+* `models.ai.azure.com` - Used for deploying Models as a Service
 
 > [!TIP]
 > If you're using hub and project workspaces, each project workspace has its own set of FQDNs. For more information, see the [workspace DNS resolution](#workspace-dns-resolution-path) section.