I setup a guest network for all my smart devices. I want to force them all to use certain DNS servers, so I went into LuCi -> Network -> Interfaces -> Guest -> DHCP Server -> Advanced Settings and updated the DHCP-Options with "6,<server 1>,<server2>". Is there a way that I can verify my smart devices are actually using these servers? I'm slightly confused about the following:
if I go into WAN -> Advanced Settings, I see "Use DNS servers advertised by peer" is checked.
This is where my misunderstanding of interfaces comes into play. If I configured DNS for one of my interfaces (in the example above, my Guest interfae. I could also do the same for my LAN interface) but keep the DNS box checked in WAN, does it override the Guest/LAN settings? Or do those interfaces resolve DNS queries separately from WAN? If it's separate, which clients does the WAN resolve DNS queries for?
Just to make sure I understand-- basically, there's nothing I can do to prevent devices from trying to intercept DNS but if I follow the guide then I can workaround it?
I can run that from my laptop or something. Does that ensure that all other devices connected to the network will also use the same servers?
edit: I see, I can run tcpdump if I ssh into the router. I suppose I could filter out traffic from the device for port 53 and inspect the response. Does that sound right?