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.