If you are using Oracle Names as a naming method, you can specify the name and address of preferred Oracle Names servers to take precedence over any other available Oracle Names server addresses. Oracle Net routes name resolution requests to each preferred Oracle Names Server until a response is received.
Preferred Oracle Names servers are an alternative to using the Discover Oracle Names Servers command. This command create a list of Oracle Names servers based on what is available throughout the network and ranks them in the order of fastest response time. Preferred Oracle Names servers override any other Oracle Names servers found during the discovery process. Once you have initially discovered an Oracle Names server, you may want to delete preferred Oracle Names servers.
To specify a preferred Oracle Names server:
In the navigator pane, expand Oracle Net Configuration > Local > Profile
From the list in the right pane, select Preferred Names Servers.
Choose New. A Preferred Names Server tab appears.
Select a protocol and enter the appropriate protocol parameter information for the selected protocol.
Repeat steps 3 and 4 for each additional protocol address. The first address in the list will be contacted first.
Choose File > Save Network Configuration.