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# System prepended metadata

title: Troubleshoot and Debug Web Applications
tags: [Certification, Microsoft]

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#  Troubleshoot and Debug Web Applications
*This portion takes up 20-25% of the exam*

### Prevent and troubleshoot runtime issues
Troubleshoot performance, security, and errors; implement tracing, logging, and debugging including IntelliTrace; enable and configure health monitoring including Performance Monitor; configure and use App Insights runtime telemetry

### Design an exception handling strategy
Handle exceptions across multiple layers; use MVC middleware to configure error handling; use different exception handling strategies for different environments; create and display custom error pages; configure a custom pipeline for error handling; handle first chance exceptions; configure and use App Insights; log application exceptions

### Test a web application
Create and run unit tests, for example, use the Assert class, create mocks and stubs; create and run web tests including using Browser Link; debug a web application in multiple browsers and mobile emulators; use Azure DevTest Labs; use Visual Studio Team Services

### Debug an Azure application
Collect diagnostic information by using Azure App Insights; choose log types, for example, event logs, performance counters, and crash dumps; stream logs directly to Visual Studio from a deployed site; debug an Azure application by using Visual Studio and remote debugging; interact directly with remote Azure websites using Server Explorer

### Preparation resources
* [Using shims to isolate your application from other assemblies for unit testing](http://msdn.microsoft.com/en-us/library/hh549176(v=vs.120).aspx)

###### tags: `Microsoft` `Certification`