In Internet Information Services (IIS) 7.0, request routing modules such as Microsoft Application Request Routing can transform the server that is running IIS into a proxy server. In this case, the IIS proxy server can forward requests to other destinations. However, a request is rejected if the following conditions are true:

• The requested file already exists on the local IIS proxy server.
• The system access control list (SACL) of the requested file does not give the access permission to the user who makes the request.

Additionally, the performance is decreased if the following conditions are true:

• The requested file already exists on the local IIS proxy server.
• The system access control list (SACL) of the requested file gives the access permission to the user who makes the request.

Note: The performance is decreased even if the requested file does not exist on the IIS proxy server.