I have setup a DDNS with DNS-O-MATIC using the DDNS LuCI app. I then set the DNS to the OpenDNS DNS servers, you login into your dashboard and you can do domain blocking and content filtering.
To cut a long story short I would like all my traffic to use the OpenDNS DNS's and I would like to stop any clients from overriding the DNS with a custom one like Google's (220.127.116.11).
My question is where do I actually set the DNS? There's three places I can think of:-
Network > Interfaces > WAN > Common Configuration > Advanced Settings > Use custom DNS servers
Network > Interfaces > LAN > DHCP Server > Advanced Settings > DHCP-options
Network > DHCP and DNS > Server Settings > DNS forwardings