Exam AZ-220 topic 3 question 18 discussion

Actual exam question from Microsoft's AZ-220

Question #: 18
Topic #: 3

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You are developing a custom Azure IoT Edge module.
The module needs to identify the device ID of the local device.
Solution: You configure the module to read the device ID of the device twin.
Does this meet the goal?

A. Yes
B. No

Show Suggested Answer

Suggested Answer: A 🗳️
Device twins are JSON documents that store device state information including metadata, configurations, and conditions. Azure IoT Hub maintains a device twin for each device that you connect to IoT Hub.
Device identity properties. The root of the device twin JSON document contains the read-only properties from the corresponding device identity stored in the identity registry.
Reference:
https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-device-twins

by theScriptingEngineer at March 29, 2022, 11:50 a.m.

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theScriptingEngineer

3 years, 3 months ago

As far as I know, the full device twin is only available in the cloud for back-end apps. The IoT Edge only gets the desired properties part of the device twin

upvoted 3 times

trahd

2 years, 2 months ago

I can confirm your statement in testing with C#. From a code snippet ... s_deviceClient = DeviceClient.CreateFromConnectionString(s_connectionString, Microsoft.Azure.Devices.Client.TransportType.Mqtt_Tcp_Only); var twin = await s_deviceClient.GetTwinAsync(); Console.WriteLine(twin.ToJson( Formatting.Indented)); ... Got the following output: { "deviceId": null, "etag": null, "version": null, "properties": { "desired": { "FPS": 45, "$version": 5 }, "reported": { "$version": 1 } } } Other Notes: SDK: Microsoft.Azure.Devices.Client version 1.41.3.0 .NET 7.02 Tested on non-IoT Edge device but I don't expect that to make a difference.

upvoted 1 times

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