The system.webServer section of the Web.config file lists the IIS 7.0 settings that apply to the web application. System.WebServer is a child of the configuration section. For more information, see IIS 7.0: system.webServer Section Group (IIS Parameter Diagram).
<system.web> ASP.NET , - ASP.NET . httpHandlers handlers .
HTTP IIS 6.0, :
<configuration>
<system.web>
<httpHandlers>
<add verb="*" path="SampleHandler.new"
type="SampleHandler, SampleHandlerAssembly" />
</httpHandlers>
</system.web>
</configuration>
HTTP IIS 7.0 :
<configuration>
<system.web>
<httpHandlers>
<add verb="*" path="SampleHandler.new"
type="SampleHandler, SampleHandlerAssembly" />
</httpHandlers>
</system.web>
<system.webServer>
<add name=SampleHandler" verb="*" path="SampleHandler.new"
Modules="IsapiModule"
scriptProcessor="FrameworkPath\aspnet_isapi.dll"
resourceType="File" />
</system.webServer>
</configuration>