In addition to client-side load balancing, Oracle Net Services include connection failover. If an error is returned from the chosen address in the list, Oracle Net Services tries the next address in the list until it is either successful or it has exhausted all addresses in its list. For SCAN, Oracle Net Services tries all three addresses before returning a failure to the client. EZConnect with SCAN includes this connection failover feature.
To increase availability, you can specify a timeout that specifies how long Oracle Net waits for a response from the listener before returning an error. The method of setting this timeout parameter depends on the type of client access. Oracle Net maintains these parameters for backward compatibility.
This section includes the following topics: