Hi mrcm,
It really depends on what you mean by "full functionality". Please see individual explanations below.
1. Distribution servers are used to distribute policies and help with various tasks, they are only needed when your environment is too large to be handled by just the one ENTM server.
2. You do need either and MSSQL DB or an Oracle SQL DB in order to install ENTM. For more info, see 'Server' section of the compatibility matrix link from my first post.
3. UARM is used to monitor user activity and provides reports on 'who used what'.
4. ObserveIT is used for session recordings of Windows RDP sessions. This is no longer "needed" in 12.9+ because of the new PROXY_RDP functionality which can replace it without the need for the additional licensing and install requirements of ObserveIT.
5. The reporting server is used to generate reports on things like 'who has access to what'.
We would not recommend grouping any of these together on the same server.
-Christian