Single Client Access Name (SCAN) is an Oracle Grid Infrastructure feature that provides a single name for clients to access Oracle databases running in a cluster.
By default, every database deployment on Oracle Database Exadata Cloud Service is associated with a SCAN, and the SCAN is associated with 3 virtual IP addresses (VIPs). Each SCAN VIP is also associated with a SCAN listener, that provides a connection endpoint for Oracle database connections using Oracle Net Services. To maximize availability, Oracle Grid Infrastructure distributes the SCAN VIPs and SCAN listeners across the available cluster nodes. In addition, the SCAN VIPs and SCAN listeners are automatically migrated to a surviving node in the case of node shutdown or failure. The aim is to ensure that Oracle clients always have a single, reliable set of connection endpoints that can service all of the databases running in the cluster.
You can define a custom host name for the SCAN VIP addresses associated with Exadata Cloud Service. To do so, contact the administrator of your DNS (Domain Name Service) and request a custom DNS record that resolves to all three of the SCAN VIP addresses. For example, if your domain is
example.com and you wanted to use
db1scan as the custom SCAN host name, you would request a DNS record that resolves
db1scan.example.com to the three SCAN VIP addresses associated with your database deployments. You can obtain the SCAN VIP addresses by viewing details as described in Viewing Detailed Information for a Database Deployment.