Chapter 3 Authentication for FortiOS 5.0 : Agent-based FSSO : Troubleshooting FSSO : Can’t find the DCagent service
  
Can’t find the DCagent service
The DCagent service can’t be found in the list of regular windows services. This is because it has no associated Windows service.
Instead DCagent is really dcagent.dll and is located in the Windows\system32 folder. This DLL file is loaded when windows boots up and it intercepts all logon events processed by the domain controller to send these events to the Collector agent (CA).