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When Pi-hole is down?

I have an asus router with a pi-hole on the network.

I was doing some work on my server and noticed that when pi-hole was down, I couldn't access the internet. I was looking for some ideas online how to deal with this, but they said to have a second pihole on the network in case one is offline. Is that the only way to do it? Is there any way to have the network go back to normal if the pihole is offline?

MangoPenguin ,
@MangoPenguin@lemmy.blahaj.zone avatar

One option is just do a temporary change on your PC to different DNS servers while you work on the stuff.

Otherwise a second PiHole set as the secondary DNS in DHCP would keep things online.

machinin OP ,

Thanks. Yeah, that is what I did during maintenance, but I'm trying to think what happens if I'm gone and my family has issues.

SpaceCadet ,
@SpaceCadet@feddit.nl avatar

Otherwise a second PiHole set as the secondary DNS in DHCP would keep things online.

No, that just creates time outs and delays when either of them is offline.

The proper way is to have a standby pihole that takes over the IP address of the main pihole when it goes down. It's quite easy to achieve this with keepalived.

atzanteol ,

I was doing some work on my server and noticed that when pi-hole was down, I couldn't access the internet.

You've opted to take control over a critical piece of network infrastructure. This is to be expected.

There's a reason DHCP provides for multiple DNS servers to be listed. Having redundant DNS servers is a common setup. So yes, multiple piholes if you want stability.

CurbsTickle ,

Just wanted to add onto your comment for clarity for others, the multiple servers are not redundancy so much as first come first serve, which is why your comment of multiple pi-holes is important.

If you were to list a pihole and say Google DNS as primary and secondary respectively, you may have some DNS queries responded to by Google. Negating the point of having a pi-hole or similar DNS service locally.

A secondary can be a docker container, another physical pi-hole (even a zero-w, which I personally don't recommend being your only way to manage DNS, but is fine when you just need to do some maintenance on the primary).

AceBonobo ,

Could have pihole running on your desktop as a backup

redcalcium ,

Another trick is setting up a guest/secondary AP that don't use pi-hole. When your pihole is down, just switch to the secondary AP. Most routers can setup multiple APs, though not all can setup different dns server for the other APs.

machinin OP ,

Thanks, that might work. I'll check into it.

elDalvini ,

I have my pi-hole setup as the upstream DNS in my router, with cloudflare as a secondary DNS. That way, all my devices always use the router for DNS (since that's what is advertised in my DHCP) and the router then uses pi-hole if it's available, or cloudflare if it isn't. But the individual device doesn't get to choose between different servers.

taladar ,

The vast majority of devices that allow setting multiple DNS servers do not strictly prioritise one over the other even if they label it as primary and secondary.

elDalvini ,

That's why I don't let every device decide individually. I know my router (FritzBox) prioritizes the pi-hole (it's even called "preferred" and "alternative" DNS-Server in the UI)

taladar ,

Those labels are quite common too with systems that do not prioritize one over the other.

AtariDump ,

When it comes to a “secondary”DNS... there is nothing like a primary and secondary DNS server. These indications are quite misleading but many systems adopted it this way. Pihole only list the DNS servers as primary and secondary, because this is what the providers write on their pages. The bad phrasing is supported especially by how Windows handles it.

Most operating systems implement DNS servers 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) [if you specify a secondary DNS server on your network].

The ONLY DNS server you should have set on your network is a/the PiHole(s).

HybridSarcasm Mod ,
@HybridSarcasm@lemmy.world avatar

Add another DNS server (1.1.1.1, for instance) to your DHCP options. Your DHCP clients will use 1.1.1.1 when the pi-hole isn’t responsive.

Rooki ,
@Rooki@lemmy.world avatar

Does it really do that? I thought if pi-hole blocks it, it just says nothing here, normally a pc then looks up your secondary dns and then ads are back at it.

This was my experience when i did that.

HybridSarcasm Mod , (edited )
@HybridSarcasm@lemmy.world avatar

Yes, your experience will be different if your DNS is being provided by another kind of DNS resolver. If you want a consistent pi-hole experience (and you can’t avoid downtime of your current pi-hole), add another pi-hole to your network and let that be your secondary DNS resolver.

taladar ,

No, that is not how DNS blocking works. It doesn't just avoid responding, it responds but with a response that says that the domain does not exist or one that points to a different IP address.

1984 ,
@1984@lemmy.today avatar

Yeah this is the next best option, but a secondary pihole is the best, so you still get the dns blocking while the first one is down.

You listed cloudflare now (1.1.1.1) but I prefer https://www.quad9.net/ for the privacy and security.

AtariDump ,

When it comes to a “secondary”DNS... there is nothing like a primary and secondary DNS server. These indications are quite misleading but many systems adopted it this way. Pihole only list the DNS servers as primary and secondary, because this is what the providers write on their pages. The bad phrasing is supported especially by how Windows handles it.

Most operating systems implement DNS servers 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) [if you specify a secondary DNS server on your network].

The ONLY DNS server you should have set on your network is a/the PiHole(s).

1984 ,
@1984@lemmy.today avatar

Didn't know that, thanks for clarification!

Then I suggest two piholes. :)

hi_its_me ,

I don’t think this accomplishes what he wants. The router DHCP will assign the second DNS address as you mention, but the devices will select one at random, not as a backup/failover. So what happens is that devices sometimes go through the Pi-hole and sometimes go through the secondary DNS address and receive ads. The only real way I’m aware of is to have a second pi-hole for redundancy. Personally, I decided to use a cloud based service (NextDNS) for this exact reason. I didn’t want my families internet to rely on devices that I host.

machinin OP ,

How many queries a month do you have? I'm at 15 days and I'm already at 750K. Do you pay for your service? I can do that, just curious what is common.

BearOfaTime ,

I'm at 30k blocked per day, over 100k queries per day.

This on a small 2 user network, with a handful of machines, but a fucking Samsung TV. That goddamn thing constantly pings all sorts of shit.

If I really restrict it (breaking some stuff on the TV), I can get to 35% of queries blocked per day, mostly from it.

Though nominal blocking kills the ads on the menu system, pretty well, making it much more responsive.

hi_its_me ,

I’m not exactly sure how many queries, but it’s above the free limit. I purchased the pro plan. For $20 a year and it’s been a great service for me. I can send a referral code for 30% off (I think). I think adguard has a similar service.

magikmw ,

I think it depends. In my limited experience, because I have not tested this thoroughly, most systems pick the first DNS adresses and only send requests to the second if first doesn't respond.

This has lead at least a couple of times to extremely long timeouts making me think the system is unresponsive, especially with things like kerberos ssh login and such.

I personally set up my DHCP to provide pihole as primary, and my off site IPA master as secondary (so I still have internal split brain DNS working in case the entire VM host goes down).

Now I kinda want to test if that offsite DNS gets any requests in normal use. Maybe would explain some ad leaks on twitch.tv (likely twitch just using the same hosts for video and ads, but who knows).

Edit: If that is indeed the case, I'm not looking forward to maintaining another pihole offsite. Ehhh.

CurbsTickle ,

It is entirely the case.

DNS queries will go to all on the list, and use whatever responds first.

If you are seeing occasional ad leaks, this is why.

AtariDump ,

When it comes to a “secondary”DNS... there is nothing like a primary and secondary DNS server. These indications are quite misleading but many systems adopted it this way. Pihole only list the DNS servers as primary and secondary, because this is what the providers write on their pages. The bad phrasing is supported especially by how Windows handles it.

Most operating systems implement DNS servers 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) [if you specify a secondary DNS server on your network].

The ONLY DNS server you should have set on your network is a/the PiHole(s).

rambos ,

Wait, but then you cant tell if your device will use pihole even if its up. Afaik primary/secondary dns is not used in that order. I think best way is to set up 2nd pihole

atzanteol ,

They will also use 1.1.1.1 whenever they want. The order is not guaranteed.

Hosts also tend to use the same one for some time, so if your pihole went down clients may still favor 1.1.1.1 even after it comes back up.

AtariDump ,

When it comes to a “secondary”DNS... there is nothing like a primary and secondary DNS server. These indications are quite misleading but many systems adopted it this way. Pihole only list the DNS servers as primary and secondary, because this is what the providers write on their pages. The bad phrasing is supported especially by how Windows handles it.

Most operating systems implement DNS servers 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) [if you specify a secondary DNS server on your network].

The ONLY DNS server you should have set on your network is a/the PiHole(s).

HybridSarcasm Mod ,
@HybridSarcasm@lemmy.world avatar

Except when the ONLY pi-hole is down, which was the original OP’s whole question.

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