title: How to find out where a handler mapping is being inherited from in IIS
body: <p>Here's my problem. I'm installing a module that the company I work for developed in a version 5.0.4 DotNetNuke installation.</p>
  
  <p>The .dnn manifest file has a nodes section that includes this add</p>
  
  <pre><code>&lt;node path="/configuration/system.webServer/handlers" 
      action="update" key="name" collision="overwrite"&gt;
      &lt;add name="svc-Integrated" verb="*" path="*.svc"
       type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=1111111111111111" resourceType="Unspecified" 
          preCondition="integratedMode"/&gt;
  &lt;/node&gt;
  </code></pre>
  
  <p>The web.config for the DNN application does not already have this add in the configuration/system.webServer/handlers section so it adds it to the web.config.</p>
  
  <p>Then when trying to load the web site, I get an error saying:</p>
  
  <pre><code>Cannot add duplicate collection entry of type 'add' with 
      unique key attribute 'name' set to 'svc-Integrated'
  </code></pre>
  
  <p>I've spent some time looking for where this duplicate entry for svc-Integrated could be coming from, and finally found out to look in IIS at the Web Site the DNN web application is under. It has a section for <em>Handler Mappings</em>, and the svc-Integrated tag is in there for the web site, with an <strong>Entry Type</strong> of <strong>Inherited</strong>.</p>
  
  <p>I'm trying to find out where the svc-Integrated handler is being inherited from.</p>
  
  <p>Edit: I've looked through <em>c:\windows\Microsoft.NET\Framework\v2.0.50727\CONFIG</em> at the <em>machine.config</em> and <em>web.config</em> files, and there are no entries at all that say "svc-Integrated" for the name. I tried looking in the <em>Framework64</em> folder and the v4.* folder under each at the <em>machine.config</em> and <em>web.config</em> and there are no svc-Integrated in <strong>ANY</strong> of those locations, so I don't have the slightest clue where IIS is getting this handler definition from :(</p>