Before a node agent can manage server instances, it must be running. Start a node agent by running the asadmin command start-node-agent locally on the system where the node agent resides.
For a complete description of the command syntax, see the online help for the command.
For example:
asadmin start-node-agent --user admin --startinstances=false nodeagent1
where admin is your administration user, and nodeagent1 is the node agent being started. Next, use asadmin start-instance command to start the server instance.