oracle 11g RAC public/virtual/SACN/private IP we need to know

1.3.2.2 IP Address Requirements

Before starting the installation, you must have at least two interfaces configured on each node: One for the private IP address and one for the public IP address.

1.3.2.2.1 IP Address Requirements for Manual Configuration
If you do not enable GNS, then the public and virtual IP addresses for each node must be static IP addresses, configured before installation for each node, but not currently in use. Public and virtual IP addresses must be on the same subnet.

Oracle Clusterware manages private IP addresses in the private subnet on interfaces you identify as private during the installation interview.

The cluster must have the following addresses configured:

A public IP address for each node, with the following characteristics:

Static IP address

Configured before installation for each node, and resolvable to that node before installation

On the same subnet as all other public IP addresses, VIP addresses, and SCAN addresses

A virtual IP address for each node, with the following characteristics:

Static IP address

Configured before installation for each node, but not currently in use

On the same subnet as all other public IP addresses, VIP addresses, and SCAN addresses

A Single Client Access Name (SCAN) for the cluster, with the following characteristics:

Three Static IP addresses configured on the domain name server (DNS) before installation so that the three IP addresses are associated with the name provided as the SCAN, and all three addresses are returned in random order by the DNS to the requestor

Configured before installation in the DNS to resolve to addresses that are not currently in use

Given a name that does not begin with a numeral

On the same subnet as all other public IP addresses, VIP addresses, and SCAN addresses

Conforms with the RFC 952 standard, which allows alphanumeric characters and hyphens ("-"), but
does not allow underscores ("_").

A private IP
address for each node, with the following characteristics:

Static IP address

Configured before installation, but on a separate, private network, with its own subnet, that is not resolvable except by other cluster member nodes

Note:
Oracle strongly recommends that you do not configure SCAN VIP addresses in the hosts file. Use DNS resolution for SCAN VIPs. If you use the hosts file to resolve SCANs, then you will only
be able to resolve to one IP address and you will have only one SCAN address.