To implement GNS, your network administrator must configure the DNS to set up a domain for the cluster, and delegate resolution of that domain to the GNS VIP. You can use a separate domain, or you can create a subdomain of an existing domain for the cluster.
GNS distinguishes between nodes by using cluster names and individual node identifiers as part of the host name for that cluster node, so that cluster node 123 in cluster A is distinguishable from cluster node 123 in cluster B.
However, if you configure host names manually, then the subdomain you delegate to GNS should have no subdomains. For example, if you delegate the subdomain mydomain.example.com to GNS for resolution, then there should be no other.mydomain.example.com domains. Oracle recommends that you delegate a subdomain to GNS that is used by GNS exclusively.
Note:
You can use GNS without DNS delegation in configurations where static addressing is being done, such as in Oracle Flex ASM or Oracle Flex Clusters. However, GNS requires a domain be delegated to it if addresses are assigned using DHCP.
Example 2-1 shows DNS entries required to delegate a domain called myclustergns.example.com to a GNS VIP address 10.9.8.7:
See Also:
Oracle Grid Infrastructure Installation Guide for more information about network domains and delegation for GNS
The GNS daemon and the GNS VIP run on one node in the server cluster. The GNS daemon listens on the GNS VIP using port 53 for DNS requests. Oracle Clusterware manages the GNS daemon and the GNS VIP to ensure that they are always available. If the server on which the GNS daemon is running fails, then Oracle Clusterware fails over the GNS daemon and the GNS VIP to a surviving cluster member node. If the cluster is an Oracle Flex Cluster configuration, then Oracle Clusterware fails over the GNS daemon and the GNS VIP to a Hub Node.
Note:
Oracle Clusterware does not fail over GNS addresses to different clusters. Failovers occur only to members of the same cluster.
See Also:
Oracle Flex Clusters for more information about Oracle Flex Clusters and GNS
Example 2-1 DNS Entries
# Delegate to gns on mycluster mycluster.example.com NS myclustergns.example.com #Let the world know to go to the GNS vip myclustergns.example.com. 10.9.8.7