- rac1.dbaora.com
- rac2.dbaora.com
public | private | vip | |
rac1 | 192.168.0.50 | 192.168.56.60 | 192.168.0.70 |
rac2 | 192.168.0.51 | 192.168.56.61 | 192.168.0.71 |
with single client access name (SCAN) address
public | |
rac-scan | 192.168.0.20 192.168.0.21 192.168.0.22 |
My WIFI router generates ip adress like 192.168.1.X so it doesn’t interfere with RAC public, private and SCAN. It’s important to have your internet network on separate subnet.
So my entry in “/ect/hosts” looks following. As you can notice SCAN entries are commented and will be resolved via dnsmasq.
127.0.0.1 localhost.localdomain localhost #public 192.168.0.50 rac1 rac1.dbaora.com 192.168.0.51 rac2 rac2.dbaora.com #private 192.168.56.60 rac1-priv rac1-priv.dbaora.com 192.168.56.61 rac2-priv rac2-priv.dbaora.com #virtual 192.168.0.70 rac1-vip rac1-vip.dbaora.com 192.168.0.71 rac2-vip rac2-vip.dbaora.com #scan #192.168.0.20 rac-scan rac-scan.dbaora.com #192.168.0.21 rac-scan rac-scan.dbaora.com #192.168.0.22 rac-scan rac-scan.dbaora.com
Install and configure dnsmasq
1. To install dnsmasq run as root following command
yum install dnsmasq
2. Configure dnsmasqcreate new file “/etc/racdns” with settings for SCAN
[root@rac1 ~]# cat /etc/racdns #scan 192.168.0.20 rac-scan rac-scan.dbaora.com 192.168.0.21 rac-scan rac-scan.dbaora.com 192.168.0.22 rac-scan rac-scan.dbaora.com
modify dnsmasq default configuration file “/etc/dnsmasq.conf”. One parameter addn-hosts should be changed to point to file “/etc/racdns”.
[root@rac1 ~]# cat /etc/dnsmasq.conf | grep addn-hosts addn-hosts=/etc/racdns
3. Start dnsmasq
4. Next step is to resolve problem with file “/etc/resolv.conf”service dnsmasq start chkconfig dnsmasq on
I’m using third network card as NAT with DHCP so each time you restart network card or reboot host the file is overwritten with automatically generated settings. Nameserver points for 192.168.1.1 which is required to resolve internet entries but not enough to resolve SCAN settings via dnsmasq.
As default dnsmasq is running on ip adress 127.0.0.1 so it requires following settings in “/etc/resolv.conf”.[root@rac1 ~]# cat /etc/resolv.conf # Generated by Networkmanager search dbaora.com nameserver 192.168.1.1
You must protect the file from being automatically overwritten by host reboot, network card restart etc.[root@rac1 ~]# cat /etc/resolv.conf # Generated by Networkmanager nameserver 127.0.0.1 search dbaora.com nameserver 192.168.1.1
Verification[root@rac1 ~]# chattr +i /etc/resolv.conf
It’s just running nslookup to verify all is working fine
rac-scan
rac1, rac2, rac1-priv, rac2-priv, rac1-vip, rac2-vip[root@rac1 ~]# nslookup rac-scan Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac-scan.dbaora.com Address: 192.168.0.22 Name: rac-scan.dbaora.com Address: 192.168.0.20 Name: rac-scan.dbaora.com Address: 192.168.0.21 [root@rac1 ~]# nslookup rac-scan Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac-scan.dbaora.com Address: 192.168.0.20 Name: rac-scan.dbaora.com Address: 192.168.0.21 Name: rac-scan.dbaora.com Address: 192.168.0.22 [root@rac1 ~]# nslookup rac-scan Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac-scan.dbaora.com Address: 192.168.0.21 Name: rac-scan.dbaora.com Address: 192.168.0.22 Name: rac-scan.dbaora.com Address: 192.168.0.20
Have a fun[root@rac1 ~]# nslookup rac1 Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac1.dbaora.com Address: 192.168.0.50 [root@rac1 ~]# nslookup rac2 Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac2.dbaora.com Address: 192.168.0.51 [root@rac1 ~]# nslookup rac1-priv Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac1-priv.dbaora.com Address: 192.168.56.60 [root@rac1 ~]# nslookup rac2-priv Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac2-priv.dbaora.com Address: 192.168.56.61 [root@rac1 ~]# nslookup rac1-vip Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac1-vip.dbaora.com Address: 192.168.0.70 [root@rac1 ~]# nslookup rac2-vip Server: 127.0.0.1 Address: 127.0.0.1#53 Name: rac2-vip.dbaora.com Address: 192.168.0.71
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