this post was submitted on 12 Mar 2025
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Currently have nice long docker compose file that hosts my PiHole V6 container (along with a bunch of other containers) however, reason i ask this question is because whenever I go to pull an updated image and recreate the container I experience about 20 minutes of no DNS resolution which to my knowledge is due to the NTP clock being out of sync.

What’s the best way to host a DNS sinkhole/resolver that can mitigate this issue?

Was thinking of utilizing Proxmox & LXC but I suspect I’ll get the same experience.


~~Update: Turns out PiHole doesn’t support two instances, I got both of them on separate devices also set the 2nd DNS server in my routers WAN & LAN DNS settings which did in fact split DNS between both instances however, I lost access to my routers web-ui, my Traefik instance & reverse proxies died and I lost all internet access.~~

~~So, don’t do what I did.~~

Update 2: So everything I said in my first update let’s disregard that, turns out I had my router forcing all DNS to PiHole server 1 which caused my issues mentioned above.

Two servers appears to work!

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[–] [email protected] 13 points 4 days ago (17 children)

If you run a single DNS server, you will always have downtime when it's restarted.

The only way to mitigate that, is to run 2 DNS servers.

I setup my network to use pihole as the first DNS and the router as the second, most of the time pihole is used. Unless it's down

[–] [email protected] 9 points 4 days ago (3 children)

How do you set up clients so they will always use the first one? I thought if a client knows 2 servers they will switch between them.

I plan to add a second Pihole at some point and keep them synced

[–] [email protected] 3 points 4 days ago (1 children)

Are you using pihole to also create custom local DNS records?

[–] [email protected] 2 points 4 days ago

Yes, mostly just the hostnames

[–] [email protected] 9 points 4 days ago (1 children)

Yeah, you can't. There is no guarantee that clients will use dns servers in any particular order.

[–] [email protected] 1 points 3 days ago (1 children)

Not that it particularly matters for just queries. The problem is that DHCP can only be enabled on one host. If that one fails then devices can't get on to the network themselves. I'd like to know a good way to have a failover DHCP server - my janky cronjob isn't great.

[–] [email protected] 2 points 2 days ago (1 children)

You can just run two DHCP servers. Give them non-overlapping ranges or give them the same MAC to IP mapping.

[–] [email protected] 2 points 2 days ago (1 children)

How do the DNS servers resolve local hostnames then? The pihole DHCP integration adds local hostnames to DNS when they are assigned an address. If there's two DHCP servers handing out leases, presumable only one would be accepted, how then would the DNS servers sync those names?

I think I had my secondary pihole resolve local names from the primary, and leases were copied over on a cronjob in case the secondary DHCP server had to be enabled.

[–] [email protected] 2 points 2 days ago* (last edited 2 days ago)

Use the second option of a static MAC to IP map and add the relevant records to each pihole’s local DNS.

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