Dnsmasq : For Simple DNS Configurations
Dnsmasq is a simple way to set up a DNS server for a small network, rather than going to the trouble of configuring BIND.
The Dnsmasq service is installed from a Yum repository using the following command.
# yum install dnsmasq
Turn on the Dnsmasq server and make sure it starts automatically on reboot.
# service dnsmasq start # chkconfig dnsmasq on
Dnsmasq is configured by altering the contents of the "/etc/dnsmasq.conf" file and the contents of the "/etc/hosts" file.
The service can be stopped, started and restarted using the following commands.
# service dnsmasq stop # service dnsmasq start # service dnsmasq restart
If you are using the Linux firewall, you need to open port 53 specifically.
For the iptables firewall, use the following commands.
# iptables -I INPUT -p tcp --dport 53 -j ACCEPT # iptables -I INPUT -p udp --dport 53 -j ACCEPT # service iptables save
For the firewalld firewall, use the following commands to open the port for the current runtime and permanently to persist through reboots.
# firewall-cmd --zone=public --add-port=53/tcp # firewall-cmd --zone=public --add-port=53/udp # firewall-cmd --permanent --zone=public --add-port=53/tcp # firewall-cmd --permanent --zone=public --add-port=53/udp
You don't need to do any specific DNS configuration as Dnsmasq will use the contents of the "/etc/hosts" to resolve any name requests. Anything it can't find there will be forwarded to the nameservers listed in the "/etc/resolv.conf" file.
For example, adding the following entries to the "/etc/hosts" file on the server running Dnsmasq, will allow it to act as a DNS, resolving those names.
# Oracle Linux 6 - RAC Installation 192.168.0.111 ol6-112-rac1.localdomain ol6-112-rac1 192.168.0.112 ol6-112-rac2.localdomain ol6-112-rac2 192.168.1.111 ol6-112-rac1-priv.localdomain ol6-112-rac1-priv 192.168.1.112 ol6-112-rac2-priv.localdomain ol6-112-rac2-priv 192.168.0.113 ol6-112-rac1-vip.localdomain ol6-112-rac1-vip 192.168.0.114 ol6-112-rac2-vip.localdomain ol6-112-rac2-vip 192.168.0.115 ol6-112-scan.localdomain ol6-112-scan 192.168.0.116 ol6-112-scan.localdomain ol6-112-scan 192.168.0.117 ol6-112-scan.localdomain ol6-112-scan
Any machines in the network that need to use this DNS server for name resolution need their "/etc/resolv.conf" file amended so the "nameserver" entry points at this server.
search localdomain nameserver 192.168.0.4
For more information see:
- Linux DNS Configuration
- DNS Configuration for the SCAN used with Oracle RAC Database 11g Release 2
Hope this helps. Regards Tim...