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What is IIS modules as the root cause?


Trying to find the root cause of a response degradation.

DynaTrace shows that top findings as IIS Modules.

Time consumed by IIS modules is equal to response time of the degraded response.

Further clicking on IIS modules there is a breakdown which says 'General' (100%)




Did you turned on on host (edit settings) beta support for IIS modules? Than you will see list of those modules with response time contribution. In General IIS is webServer, it uses modules to handle session, transactions routing etc. Sometime those modules has issues.


Yes that is turned on.

There is a long list of modules under IIS modules on the view response time hotspots page.

Out of which it says 'General' is contributing 100% to the response degradation.

To analyse it you can check perfview to record session or debugdiag. Both are tools from microsoft. As well you can start performance monitor and check amount of requests on iis, if some of them are waiting. Maybe resources of this IIS are exhausted. Configuration is default or custom? IIS is hard to analyse, such cases needs experts from IIS. DT will not show you more.


Thanks 🙂


From my experience, a high "General" IIS module usage means the client is consuming response slowly. (Client typically has slow network connection). Thus it is not a problem of the application or IIS.

TEMPEST a.s., Slovakia, Dynatrace Master Partner

Can you say something more about it? I’ve got situations like this with couple of minutes spent on general iis module, this was during loadtests where internet connection was just fine. I’m curious about correlation here. Are you suggesting that for example iis is serving 1mb payload which is downloaded by client for some time?

From my experience with iis there aren’t only one explenation for the same symptoms. I rather prefer java applications or at least .net core for analysis 🙂


I agree, it's difficult to debug and this is not the only single explanation. However, I've done some testing and this slow network (large http responses with the combination of slow or laggy connection lead to this outcome).

TEMPEST a.s., Slovakia, Dynatrace Master Partner

Good to know for the future 🙂 I'll check this clue when I will have such issue next time