11.2 requires a Single Client Access Name (SCAN) name for the cluster (max 15 chars).

The single client access name (SCAN) is the hostname to provide for all clients connecting to the cluster.
The SCAN is a domain name registered to at least one and up to three IP addresses, either in the domain name service (DNS) or the Grid Naming Service (GNS).
The SCAN eliminates the need to change clients when nodes are added to or removed from the cluster. Clients using the SCAN can also access the cluster using EZCONNECT.

The default name for the SCAN defaults to the local node name on installation.
In a typical installation the SCAN is also the name of the cluster.

If you need to use more than 15 chars choose the advanced installation option.

The SCASN can be defined in the hosts file if required.