1. IP Addresses are configured using one of the following options :
a. Oracle Grid Naming Service (GNS) Using one static address defined during your installation.
b. Static addresses that network administrators assign on a network domain name server (DNS) for each node (In your case two nodes)
2. Public IP must registered in the domain name server (DNS) or the /etc/hosts file.
Finally, the cluster must have the following :
1. Public IP for each node
2. Virtual IP for each node
3. Private IP for each node
4. Single Client Access Name (SCAN) for the cluster