Noob question about PiHole

Kir@feddit.it to Selfhosted@lemmy.world – 29 points –

Hy everyone, I have a PiHole instance running on my home server, and I changed my router (Fritz box) DNS in order to use my PiHole. Everything runs great.

I was wondering if I can put another DNS provider on my "alternative DNS server" in my router, in order to have a fallback alternative in case my server is down, or if I should avoid it.

I'm asking this because I don't know if the request will be handled in parallel between the two DNS provider (that would make my PiHole useless) or not. Thank you.

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The issue is that according to the spec the two DNS servers provided by DHCP are equivalent. While most clients favor the first one as the default, that's not universally the case and when and how it switches to the secondary can vary by client (and effectively appear random). So you won't be able to know for sure which client uses your DNS, especially after your DNS server was unreachable for a while for whatever reason. Personally I've "just" gotten a second Pi to run redundant copies of PiHole, but only having a single DNS server is usually fine as well.

This answered my question. Thank you. I guess I will sacrifice redundancy

Or set up a second pi-hole.

I run multiple pinholes using keepalived. Then I only use one DNS in my DHCP server. Second pihole will seemlessly take over if the first one goes down whilst using the original DNS address.

Work quite well. I had to learn the hard way that only using a single pihole was just asking for my partner to be mad when it didn't work / when I was doing server maintenance. Now I have multiple and they can all seemlessly take over if any my server nodes are down

How do you manage automatically transferring the ip of the main rpi to the backup rpi when the first disappears?

clone the Mac address

Don't you then run into MAC conflicts?

How do you keep both on the network?

I'm just spit balling here: backup pi pings munute-ly main pi. if main pi is down 2 pings, it resets Mac and reboots network interface.

Then when the main PI returns it creates a conflict...

oh hm...

hmmm

ok. both pis know the live IP and the backup IP, and have the same config: cold boot into backup I and ping live ip

Keepalived is the way. Gravity sync keeps everything in line. Works like a charm. I migrated yesterday from wifi to wired and cannot be happier. As a bonus did not need to reconfigure pivpn.