Owner's Manual

Configuring Your Network 17
2 On all nodes in the cluster, edit the resolv.conf file to include name server
entries that are resolvable to DNS servers.
For example, edit the
/etc/resolv.conf file as:
options attempts: 2
options timeout: 1
search clusterdomain.example.com example.com
nameserver 192.0.2.1
nameserver 192.0.2.2
NOTE: The total time-out period which is a combination of options attempted
and options timed out should be less than 30 seconds.
Where 192.0.2.1 is the valid DNS server address and 192.0.2.2 is the GNS
Virtual IP address in your network, and
clusterdomain.example.com is
the GNS sub domain.
3 Verify the order of configuration. /etc/nsswitch.conf controls name
service Lookup order.
In some system configurations, the Network Information System (NIS)
can cause issues with Oracle SCAN address resolution. It is recommended
that you place the NIS entry at the end of the search list.
For example,
hosts: files dns nis
For a Cluster Using DNS
The basic requirements to set up an Oracle 11g R2 RAC using Oracle DNS
(without GNS) are:
1 At least two interfaces configured on each node, one for the private IP
address and one for the public IP address.
2 A SCAN NAME configured on the DNS for Round Robin resolution to
three addresses (recommended) or at least one address. The SCAN addresses
must be on the same subnet as virtual IP addresses and public IP addresses.
NOTE: For high availability and scalability, Oracle recommends that you configure the
SCAN to use Round Robin resolution to three IP addresses. The name for the SCAN
cannot begin with a numeral. For installation to succeed, the SCAN must resolve to at
least one address.