[PolicyRecordingBot] No such address

Following the steps on https://github.com/microsoftgraph/microsoft-graph-comms-samples/tree/master/Samples/V1.0Samples/LocalMediaSamples/PolicyRecordingBot#create-an-application-instance, after provisioning a Cloud services (extended support) environment with an Azure bot, I'm blocked by the following error when a worker role instance tries to startup:

Starting role... Unhandled Exception: No such host is known
at System.Net.Dns.GetAddrInfo(String name)
at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6)
at System.Net.Dns.GetHostEntry(String hostNameOrAddress)
at Sample.PolicyRecordingBot.WorkerRole.AzureConfiguration.GetInstancePublicIpAddress(String publicFqdn) in C:\Users\xgantan\execvision\microsoft-graph-comms-samples\Samples\V1.0Samples\LocalMediaSamples\PolicyRecordingBot\WorkerRole\AzureConfiguration.cs:line 381
at Sample.PolicyRecordingBot.WorkerRole.AzureConfiguration.Initialize() in C:\Users\xgantan\execvision\microsoft-graph-comms-samples\Samples\V1.0Samples\LocalMediaSamples\PolicyRecordingBot\WorkerRole\AzureConfiguration.cs:line 231
at Sample.PolicyRecordingBot.WorkerRole.AzureConfiguration..ctor(IGraphLogger logger) in C:\Users\xgantan\execvision\microsoft-graph-comms-samples\Samples\V1.0Samples\LocalMediaSamples\PolicyRecordingBot\WorkerRole\AzureConfiguration.cs:line 118
at Sample.PolicyRecordingBot.WorkerRole.WorkerRole.OnStart() in C:\Users\xgantan\execvision\microsoft-graph-comms-samples\Samples\V1.0Samples\LocalMediaSamples\PolicyRecordingBot\WorkerRole\WorkerRole.cs:line 92
at Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment.InitializeRoleInternal(RoleType roleTypeEnum)
at Microsoft.WindowsAzure.ServiceRuntime.Implementation.Loader.RoleRuntimeBridge.

Start with Samples/V1.0Samples/LocalMediaSamples/PolicyRecordingBot/WorkerRole/AzureConfiguration.cs, especially Initialize() and GetInstancePublicIpAddress() around lines 231 and 381. Reproduce the provisioning and worker startup steps, then trace the publicFqdn used by the DNS lookup; done means the worker role starts without the “No such host is known” exception.