I want to set up my own DNS server on my home network to have more control over name resolution. So far I've just been using the standard DNS from my ISP. What do I need to watch out for to keep it running stable and prevent constant outages?
I've tried setting this up at home too and quickly ran into a couple of things. The main thing: get stable hardware (Raspberry Pi works, but not too old) and install something like Pi-hole or Unbound, that way you'll save yourself a lot of hassle. Make sure your server stays connected to the network and doesn't just go into standby, otherwise you'll be scratching your head later wondering why suddenly nothing works anymore. And configure your devices on the home network with the right DNS settings - otherwise they'll secretly keep using your ISP's and you'll be confused why all your work isn't doing anything.
If you notice your DNS keeps going down, it's usually because the hardware doesn't have enough resources or the network connection is unstable - so first check that your device is permanently plugged in and doesn't go into standby mode at some point. On the other points: static IPs for your DNS server are essential, otherwise all your devices will lose connection whenever something changes, and you need regular backups of your configuration in case something goes wrong. A redundant setup with two DNS servers (one locally, one as a fallback) prevents you from going completely offline if one fails.
Do you want to set this up just for your local network or make it accessible from outside? For home use, I'd recommend Pi-hole or AdGuard Home - they're straightforward to install and run smoothly if you set them up on a reasonably recent Raspberry Pi or an old laptop. About redundancy: definitely configure two DNS servers (primary and secondary), otherwise you'll have downtime when one machine goes down. And here's a small trick that a lot of people miss - log all your queries, at least initially. That'll help you spot whether there are any infinite loops running or if some client is hammering way too many requests and clogging everything up.
An often overlooked point is redundancy - if your server goes down, you've got no internet anymore because all the devices on your network are just waiting for it. That means you should set up at least a fallback DNS (so a second server or your ISP's DNS as a backup) so your clients don't end up completely in the dark. Most tools like Pi-hole let you configure that in the settings - do it right away before you go live.
Also important: make sure your server has a static IP on the network (fixed IP, not via DHCP), otherwise you'll lose track of it in your router at some point and all your clients will point to nothing. And if you want to block a lot of stuff (ads, trackers and so on), start small - some aggressive filter lists slow down the queries and make everything sluggish. Test it first with just a few lists and then gradually add more. Hardware-wise, an old Raspberry Pi really does the job as long as the CPU isn't completely overwhelmed - a quick look at the load (top or htop) will quickly tell you if it makes sense.
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