By default you will be using the DNS servers supplied by the ISP you subscribe with. With OpenWRT its easy to change the DNS service that you use to an alternative option. A popular option is the Google Public DNS service.
Advantages of using Google's DNS are :
- Faster web browsing
- Improved security
- No redirection
In OpenWRT to change is a simple process
- Open Luci web interface
- Select 'Network' -> 'DHCP and DNS'
- Locate 'DNS forwardings'
- Enter '18.104.22.168'
- Press '+' button to enable a second entry
- Enter '22.214.171.124'
- Select 'Save & Apply'