Request Manager uses configured rules to perform the following tasks when it encounters requests:
- Deny potentially harmful requests from entering a SharePoint farm.
- Route good requests to an available server.
- Manually optimize performance.
If using the "Request Manager service", be aware that it effectively operates as a load balancer and it needs to be correctly configured to include only the web front end servers. For more information, see Configure Request Manager in SharePoint Server 2013 in Microsoft TechNet.