IIS 8.5 is the version of IIS that ships with Windows 2012 R2, and Windows 8.1.
IIS 8.5 is the version of IIS that ships with Windows Server 2012 R2, and Windows 8.1.
IIS 8.5 includes several new features not found in IIS 8.0 or lower:
- Enhanced logging. An administrator can enable the logging of additional custom fields from request or response headers, or from server variables.
- Logging to event tracing for Windows. An administrator can enable the sending of logging information to Event Tracing for Windows (ETW).
- Dynamic Website activation. If there are a large number of configured sites (100 or greater, by default), the service will not activate any of the sites when the service is started.
- Idle Worker Process Page-Out. An administrator can enable an idle worker process to be suspended rather than terminated.