How to handle a pi-hole failure / crash?

[jfb]

There are a few things you can do for improved reliability:

1. Put your Pi's and network equipment on UPS (battery backup). This protects them against short term power loss (the most common type of power loss) and surges. Pi's can misbehave after a power loss (lost time sync, corrupted SD card, etc.)

2. Run a second Pi-Hole in parallel. It doesn't have to be on a Pi, it could be on an always on PC. The second Pi-Hole can also be a DHCP server, just put in on a different IP range.

Case in point - my Pi's, routers and modem are on UPS. Lost power this morning for about a minute. I was on the web on an iPad and the only way I knew it was that the lamp on the table went out. Power came back and everything was still running normally.

There have been some threads on this topic here and on Reddit/pihole. Here are a few examples:

Good solution to automatically revert to "normal" if Pi Hole dies?

It should certainly be possible with the gear you describe. You could set up a script on one (or both, why not?) of your BBBs and have them test dns connectivity periodically, and if it goes down for longer than you consider acceptable change the router settings away from the Pi-hole. My suggestion would be to have the script connect to your router by ssh and change the router DNS settings back away from your Pi-hole that way. (If your router supports using ssh keys for authentication all the…

Running two Piholes?

Here's my IPCONFIG: Windows IP Configuration Host Name . . . . . . . . . . . . : WorkLaptop Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : DSO-Home Ethernet adapter Ethernet: Connection-specific DNS Suffix . : DSO-Home Description . . . . . . . . . . . : Lenovo USB Ethernet Physical Address. . . . . . . . . : 00-50-B6-6…

Secondary DNS Server for DHCP

Most operating systems implement them as alternatives, not as fallbacks, i.e. they will query any of both servers from time to time, so it is quite likely that you will loose your Pi-hole filtering capabilities (at least partially). That is why we have never implemented this. This is a problem because my router requires a secondary DNS server; its not "optional", and it cannot be the same IP as the primary DNS server.