WebLogic Machine

A machine is a logical representation of the physical machine (computer) that hosts one or more WebLogic Server instances.

Oracle WebLogic Machine configuration:

If you want to run Node Manager on a machine that does not host an Administration Server, as is typical in production environments, you must create a machine configuration for each computer that runs a Node Manager process. The machine configuration includes information about the listen address and port number that the Administration Server uses to connect with the Node Manager process running on that machine.

Here are the steps for enrolling a WebLogic Node Manager with a domain.

For configuring the WebLogic Machine you have to go to the 
Domain Structure / Environment / Machines and now choose a machine.

Then click on Admin Server can communicate with the Node Manager on that machine. 
In this case the Node Manager Status is "Reachable":

The main configurations for the machine is to set the Node Manager settings :

Now on the "Servers" tab you can see the servers running on that machine as well :

Use of Node Manager:

• A Node Manager process is not associated with a specific WebLogic domain but with a machine.

• You can use the same Node Manager process to control server instances in any WebLogic  Server domain, as long as the server instances reside on the same machine as the Node  Manager process.

• Node Manager must run on each computer that hosts WebLogic Server instances. whether Administration Server or Managed Server that you want to control with  Node Manager.

 Start & Stop the Node Manager:

• To Start Node Manager: $WL_HOME\server\bin\startNodeManager.sh

• To Stop Node Manager: There is no script to stop NodeManager, you need to find process ID of Node Manager and kill it.  Kill – 9 <PID>