Single Client Access Name "SCAN" for Oracle Real application cluster 11g

I will discuss today a new feature that came up with Oracle 11g R 1.this new feature is known as single client access name(SCAN).prior to oracle 11g real application cluster the client connection will use each node virtual IP. When you add any new node or remove a node then the client tnsnames.ora needs to be updated with the new IP addition or removal.
Oracle 11G introduced the SCAN to handle this problem.The SCAN provide a single  name from clients  to access the database running in the cluster.
This is also very beneficial for client connecting using JDBC thin URLs and EZCONNECT to cluster with single hostname.

The components of the SCAN a cluster :
1-SCAN Name.
2-SCAN IP,Oracle recommends 3 IP addresses for SCAN for cluster.
3-SCAN Listener.

The SCAN Name is the cluster representative in the network .The SCAN Name has to be registered in the DNS and resolved using round-robin  algorithm.
To test the round-robin algorithm configuration just nslookup on the SCAN Name.The DNS server should return those 3 set of IP  addresses in different order each time.