After all the Oracle Names servers are created, have each Oracle Names server, except the first Oracle Names server in the administrative region, discover the other Oracle Names servers in a region. Discovery must be performed to find the other Oracle Names servers in the region..
To discover other Oracle Names servers:
In the navigator pane, expand Oracle Net Configuration > Oracle Names Servers.
Select the Oracle Names server.
From the list in the right pane, select Manage Server.
Select the Control tab.
Choose Server Operations, and then choose Start.
Choose Apply to start the Oracle Names server. The following
message appears: Server started successfully.
Choose Command > Discover Oracle Names Servers. The following message appears:
Discovered Oracle Names Server in the region. Please exit the
tool and start again.
If an Oracle Names server does not respond, a dialog will prompt you for another Oracle Names server address. If you know the network address of a particular Oracle Names server, enter it.
Choose File > Exit to exit Oracle Net Manager, and then start the tool again.