Happy New Year to all my readers. This is my first post of this year and I've started my year by building a RAC environment for the lab.
Most of us who wants to learn building Oracle RAC and its operations use Oracle VirtualBox as the virtualization software as it is free to use. You can also take a look at Workstation Pro which is a very powerful virtualization product (requires license and 60 day trail available) from VMware which is used in many companies as well or their free to use software Workstation Player which is similar to Workstation Pro with a few limitations.
One main requirement of building the RAC environment (For Oracle database versions 11gR2 or higher) is the availability of a DNS server or Oracle GNS which is used to resolve SCAN name minimum 1 up to 3 or more IP addresses (generally an odd number due high availability requirements) in a round robin fashion.
Most of the beginners use Windows OS to work on the practices until they get familiar with other OS such as Unix/Linux and hence we in this post look at how can we configure the host Windows OS to server as the DNS server for the Guest OS running on the virtualization software.
Software Installation:
We will use BIND 9 to create our DNS server on the Windows host. Download the latest version of BIND 9 from the download page and then extract the contents into a folder. I'm using 7zip software to extract and you can use any software as you wish
Once the contents are extracted, go the extracted files folder and start BINDInstall.exe as Run as Administrator
Set the Target Directory, provide service account password and confirm and click on Install.
The Target Directory provided is the software location or the BIND9 path. Once the installation is complete, click OK and exit the installer.
Configuration:
The software is installed just a few clicks. Now let us look into the configuration part. In this post we will configure a very basic DNS server config and you may have to look into the documentation of the particular software version that you have downloaded if you like to configure a sophisticated setup.
Once the software is installed, you will be able to see bin directory and etc directory under the software installation path, C:\Program Files\BIND9 in my case. We will have to create the named.conf file under etc directory. named.conf is the name server configuration file containing collection of statements using nested options surrounded by opening and closing ellipse characters, { }.
Sample reference file of my host's named.conf configuration looks like the below
// Listen only on this machine i.e localhost or from 192.168.56.1
options {
listen-on port 53 { 127.0.0.1; 192.168.56.1; };
directory "C:\Program Files\BIND9\zones";
allow-transfer { none; };
recursion no;
forwarders { 194.168.43.1; };
};
zone "selvapc.com." IN {
type master;
file "selvapc.com.zone";
allow-transfer { none; };
};
zone "56.168.192.in-addr.arpa." IN {
type master;
file "56.168.192.in-addr.arpa";
allow-update { none; };
};
Explanation of the above: 
Line 4: It is the named working directory
Line 10: Zone statement for selvapc.com zone. If you don't have a domain name defined, you can use localdomain instead of selvapc.com
$TTL 86400
@ IN SOA localhost root.localhost (
42 ; serial (d. adams)
3H ; refresh
15M ; retry
1W ; expiry
1D ) ; minimum
IN NS localhost
localhost IN A 127.0.0.1
12r1-rac1 IN A 192.168.56.101
12r1-rac2 IN A 192.168.56.102
12r1-rac1-priv IN A 192.168.1.101
12r1-rac2-priv IN A 192.168.1.102
12r1-rac1-vip IN A 192.168.56.103
12r1-rac2-vip IN A 192.168.56.104
scan-12r1 IN A 192.168.56.105
scan-12r1 IN A 192.168.56.106
scan-12r1 IN A 192.168.56.107
You can see here all these IPs can be resolved to their respective names. SCAN name has 3 IPs configured which will resolve in round robin fashion. $ORIGIN 56.168.192.in-addr.arpa.
$TTL 1H
@ IN SOA selvapc.com. root.selvapc.com. ( 2
3H
1H
1W
1H )
56.168.192.in-addr.arpa. IN NS selvapc.com.
101 IN PTR 12r1-rac1.selvapc.com.
102 IN PTR 12r1-rac2.selvapc.com.
103 IN PTR 12r1-rac1-vip.selvapc.com.
104 IN PTR 12r1-rac2-vip.selvapc.com.
105 IN PTR scan-12r1.selvapc.com.
106 IN PTR scan-12r1.selvapc.com.
107 IN PTR scan-12r1.selvapc.com.
Note, the trailing '.' is very important at all the places, else the configuration won't work as expected.- Go to Control Panel >> System and Security >> Windows Defender Firewall >> Click Advanced Settings
- Click Inbound Rules >> New Rule >> Protocol and Ports (Port) >> Next >> TCP >> Specific local ports (53) >> Next >> Allow the connection >> Next >> Check all the check boxes >> Next >> Specify a name for the rule Eg: TCP53 >> Finish
- Click Inbound Rules >> New Rule >> Protocol and Ports (Port) >> Next >> UDP >> Specific local ports (53) >> Next >> Allow the connection >> Next >> Check all the check boxes >> Next >> Specify a name for the rule Eg: UDP53 >> Finish
- Windows+R >> Type "services.msc" >> Click OK
- Search for ISC BIND service. Click Start if it is not running or Restart if it is already running
We have successfully completed the set up of DNS server on our Windows host machine.
We can now see that the SCAN name is able to resolve to 3 IP addresses. As we want this name resolution to happen in the local host or 192.168.56.1 (which serves as the IP address for the host OS in VirtualBox), we pass the third argument as localhost or 192.168.56.1.
[oracle@12r1-rac1 ~]$ [oracle@12r1-rac1 ~]$ uname -a Linux 12r1-rac1.selvapc.com 3.8.13-98.4.1.el6uek.x86_64 #2 SMP Wed Sep 23 18:46:01 PDT 2015 x86_64 x86_64 x86_64 GNU/Linux [oracle@12r1-rac1 ~]$ cat /etc/resolv.conf # Generated by NetworkManager search localdomain selvapc.com nameserver 192.168.56.1 [oracle@12r1-rac1 ~]$ nslookup scan-12r1 Server: 192.168.56.1 Address: 192.168.56.1#53 Name: scan-12r1.selvapc.com Address: 192.168.56.107 Name: scan-12r1.selvapc.com Address: 192.168.56.106 Name: scan-12r1.selvapc.com Address: 192.168.56.105 [oracle@12r1-rac1 ~]$ nslookup 192.168.56.106 Server: 192.168.56.1 Address: 192.168.56.1#53 106.56.168.192.in-addr.arpa name = 12r1-scan.selvapc.com. [oracle@12r1-rac1 ~]$All is good now and we can start building our Oracle RAC databases..
