The valid node checking feature provides the ability to configure and dynamically update a set of IP addresses or subnets from which registration requests are allowed by the listener. Database instance registration with a listener succeeds only when the request originates from a valid node. The network administrator can specify a list of valid nodes, excluded nodes, or disable valid node checking. The list of valid nodes explicitly lists the nodes and subnets that can register with the database. The list of excluded nodes explicitly lists the nodes that cannot register with the database. The control of dynamic registration results in increased manageability and security of Oracle RAC deployments.
By default, valid node checking for registration (VNCR) is enabled. In the default configuration, registration requests from all nodes within the subnet of the SCAN listener can register with the listener. Non-SCAN listeners only accept registration from instances on the local node. Remote nodes or nodes outside the subnet of the SCAN listener must be included on the list of valid nodes by using the registration_invited_nodes_alias parameter in the listener.ora file or by modifying the SCAN listener using SRVCTL.
See Also:
Oracle Database Net Services Administrator's Guide for more information about VNCR