Connection Timeout is a setting in IIS which asks the server to wait on an inactive connection before disconnecting it. You don’t want to waste memory resources on an idle connection and hence you should think twice before you make any changes to the default setting. I have seen number of times people increase Connection timeout setting in IIS 6 such that they don’t “connection timeout” when waiting for data on their Web page. You can use Performance Monitor to figure out what is the connection timeout value you need to set for your Web site, check Setting Connection Timeouts to Save Resources (IIS 6.0).

In IIS 6.0

1. Right click on Web Site (Default Web Site in our case) and click on Properties
2. Under Web Site tab under Connections you see Connection timeout
   
   

In IIS 7 / 7.5

1. Click on the Web Site (Default Web Site in our case)
2. In Actions panel, under Manage Web Site click Advanced Settings…
3. Under Behavior, expand Connection Limits and you see Connection Time-out
   
   
   
   OR
   
4. In Actions panel, under Manage Web Site –> Configure click Limits…
5. Under Connection Limits, you can set the Connection time-out setting
   
   

When you make any changes to the Connection Time-out setting for the Web site, it gets reflected in the applicationHost.config.

<limits connectionTimeout="00:02:00" />

Hope this helps,
Vivek Kumbhar