Meaning multiple DNS configurations

[jsface_live.nl]

Can somebody explain the DNS configurations on multiple places with LuCI?
The places where I can do DNS configuration:
Interface > WAN
Interface > LAN
Interface > LAN > DHCP Server > DHCP Options
DHCP and DNS > DNS forwarding
What is the meaning of the different configurations (maybe there are even more places)?

I want to pass a primairy and a secondairy DNS server to clients with DHCP, where to configure?

[trendy]

@jsface_live.nl

I want to pass a primairy and a secondairy DNS server to clients with DHCP, where to configure?

Here, as option 6.

@jsface_live.nl

Interface > LAN > DHCP Server > DHCP Options

The rest are upstream nameservers to be used by dnsmasq.

[jsface_live.nl]

So what is the meaning having multiple configurations for upstream nameservers?

[vgaetera]

Configure different dns for lans

The goals of defining different DNS in the network configuration: Make the DNS status dependent on the upstream interface status. Provide fault tolerance and load balancing for multiple upstream interfaces. I.e. it is not suitable for your task. You have the following options: Client classifying and individual options Multiple DHCP/DNS server/forwarder instances

[jsface_live.nl]

Sorry, I dont understand yet:
Means different DNS setting in Interface > WAN and Interface > LAN independent DNS setting for WAN and LAN?
If yes, should I leave these blank?
If yes, what is then the meaning of the setting with LuCI in Network>DHCP and DNS > DNS Forwardings?
Should I leave this blank too?

[trendy]

You can implement more complicated scenarios.
If you don't understand, just don't change anything and let the wan dhcp client autonegotiate with your provider the upstream nameservers.

[jsface_live.nl]

I search for information to understand what to do and why.
Thanks.