This step-by-step article describes how to monitor ASP.NET server applications. There are several ways to monitor ASP.NET applications. Monitoring a single application by using multiple methods provides additional assurance that an application is functioning and that all monitoring systems are working correctly. This article describes the major aspects of an ASP.NET application that can be monitored.

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Services

The services that follow are required for ASP.NET applications. If either of these services is stopped, ASP.NET applications do not function.

•	IIS Admin Service
•	World Wide Web Publishing Service

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Processes

The processes that follow are required for ASP.NET applications that run on Microsoft Internet Information Services (IIS) version 5.0. If either of these processes is not present, ASP.NET applications do not function.

•	Inetinfo.exe
•	Aspnet_wp.exe

The processes that follow are required for ASP.NET applications that run on IIS version 6.0. If either of these processes is not present, ASP.NET applications do not function.

•	Inetinfo.exe
•	W3wp.exe

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HTTP Responsiveness

The most effective mechanism you can use to monitor ASP.NET applications is to simulate client browser requests. Then, you must verify that a valid response is returned by the server. Ideally, the mechanism that you use to monitor will issue HTTP requests and then trigger an alarm that is based on one or more of the following criteria:

•	A key phrase does not appear in the response of the ASP.NET server.
•	The HTTP response to a request for a valid page is returned in a specified time. For example, the specified time may be less than one second.
•	The HTTP response code to a request for a valid page is 200. This indicates a successful response.
•	The HTTP response code to a request for a page that must be hidden (such as Web.config) is 500. This indicates a server error.
•	The ASP.NET_SessionID cookie is included in the response (when the application uses ASP.NET sessions).

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Performance Counters

You can monitor the following counters to see problems with ASP.NET applications. The specific threshold that you use to trigger an alarm may vary based on the application.

Performance Object	Performance Counter	Symptom of Problem
ASP.NET	Applications Running	The number changes.
ASP.NET	Requests Rejected	The number increases to more than zero.
ASP.NET	Errors Total	The number increases to more than zero or another specified threshold.

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For more information about performance counters for ASP.NET, see the .NET Framework SDK documentation or visit the following Microsoft Web site:

http://msdn.microsoft.com/library/en-us/cpguide/html/cpconperformancecountersforaspnet.asp (http://msdn.microsoft.com/library/en-us/cpguide/html/cpconperformancecountersforaspnet.asp)

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