A.Configure one Node Manager per domain (for example, if there are two domains on one machine, then you will need to configure two Node Managers).
B.Configure one Node Manager per machine with any number of WebLogic instances running on it.
C.Configure one Node Manager per machine for all WebLogic, OHS, and OEM running on the same machine.
D.Configure one Node Manager for every WebLogic instance.
E.Configure two or more Node Managers for every WebLogic instance.