I'm a PRTG newbie. I've just installed x86 PRTG on a Server 2008 R2 machine - it didn't have enough RAM for the x64 version. I installed with AutoDiscovery disabled.
In my AD domain, I created a service user account which I put into a common Server Admins group. I configured this in the Root Group in PRTG.
I picked a server on the network, which happened to be running Server 2008 R2 and IIS 7.5. I checked that the Server Admins group was a member of the local Administrators group on the target server.
In 1st group, I clicked Add Device..., entered the device name. selected an icon and selected 'Automatic device identification (detailed, may create many sensors)'. Sensors started to appear. In all, I got 85 sensors! (I can see that the 100 sensors of the free version isn't going to last long!) Most sensors are green. Three are legitimately orange. One is red and I can't see why:
App Pool _Total Down Error in Application Pool State: 'Unavailable'
It has been up, briefly, apparently:
Last Scan: Last Up: Last Down: Uptime: Downtime: Coverage: Sensor Type: Dependency: Interval: ID: 27 s 13 h 8 m 27 s 0.0736% 99.9264% 100% PerfCounter IIS Application Pool Parent every 60 s #2045
The seven actual App Pools are listed and Up/OK. _Total only exists in Perf Mon.