Hi All,
DB: 11gR2
I am a bit flustered when it comes to Scan and VIP. Here is my understanding about the same.
SCAN IP: In this a single hostname is given which is resolved to three virtual IP's later. This is done so that in case of a node failure/removal/addition there are no changes that are to be done on the client side. Hence, if a new connection comes on a failed node, the connection will be successfully failed over to the surviving nodes and also Load balancing is another purpose.
VIP: This is used for a successful failover of a new connection to a failed node or a failed listener. This mainly avoids the delay that occurs due to TCP connection time out and the new connection is failed over to the existing node.
As you can see, both the scan ip and VIP have one purpose common that is successful fail-over of a new connection in case of a node failure without the client knowing about it.
Please correct me if I am wrong
Regards