Pihole runs my site blocking as well as my DHCP server. It’s a LXC container on Proxmox. If the host goes down or there’s a network problem, I lose my DHCP server. I need a second pihole running on a separate machine to reduce downtime in case of failure. However, I have a bunch of DHCP assignments that need to be correct. The answer is https://github.com/08shiro80/gravity-sync-updated
Using ssh, inotify-tools and rsync, any changes made to the primary pihole are immediately copied to the backup instance, so whichever DHCP server responds will correctly assign addresses.