You are operating an IoT solution of 1000 field devices. After several weeks of operation, you notice that a certain group of temperature sensors cease to send telemetry in the morning hours. You suspect that some kind of connection problems block messages and you decide to create a diagnostic setting in your IoT Hub, route the resource logs to Azure Monitor Logs, and analyze the log by running the following query: 
<pre>AzureDiagnostics
| where ( ResourceType == "IOTHUBS" and 
Category == "Connections"
and Level == "Error")
</pre>
Does it help you to localize the error?

Answer options:

A.Yes
B.No

Correct Answer: A
Option A is CORRECT because to find connection related error events in the log, the “Connections” diagnostic setting has to be configured (see below), and Category == “Connections” has to be used to filter the log entries.
Option B is incorrectbecause it is the “Connections” category that is used to track errors related to the connectivity of the devices.
Diagram: 

Reference: 

https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-troubleshoot-connectivity#azure-monitor-use-logs-to-resolve-connectivity-errors