The SCAN is a domain name registered to at least one and up to three IP addresses, either in domain name service (DNS) or in Grid Naming Service (GNS).
About the SCAN
During the installation of Oracle Grid Infrastructure, several Oracle Clusterware resources are created for the SCAN.
About SCAN VIP Addresses
SCAN virtual IP addresses (VIPs) function like node VIPs. However, unlike node VIPs, SCAN VIPs can run on any node in the cluster.
About SCAN Listeners
During Oracle Grid Infrastructure installation, SCAN listeners are created for as many IP addresses as there are SCAN VIP addresses assigned to resolve to the SCAN.