We would like to setup two servers with pihole behind a load balancer for failover/capacity/redundancy.
One sticking point we have is the IP address that is cached on the downstream DNS client. If one of the pihole servers goes down, the clients would see a "Could not be found" message instead of a blank box where the ad used to be.
If we were able to set the IP address of the blocked domain to the VIP of the load balancer instead of the PI itself, this would solve the problem as the load balancer would failover to the working node.
If you could implement an option in the Settings page for a Custom Blackhole address, it would be much appreciated.