Following on from here where I talked about setting up a raspberry pi running pi-hole, its all good news. The pi has been running fine and it’s improved our browsing experience no end. However, I don’t like having a single point of failure for something as critical as DNS. Yes, if the pi fails the router does give out a secondary DNS server (18.104.22.168 as it happens) but we’ll lose the protection of DoH and also stop getting the ads filtered.
There is a solution – another pi running another instance of pi-hole. Quick and easy setup of pi-hole, plus cloudflared for DNS over HTTPS but then the question arose, how do I keep them in sync? I do use the pi-hole for some internal DNS resolution and I’d like to keep that in sync as well as the various allow/deny lists.
A quick bit of googling turned up this: Gravity Sync. Ten minutes later it was setup and the two raspberry pis were syncing seamlessly. Job done.