Some ways DNS can break

When I first learned about it, DNS didn’t seem like it should be THAT complicated. Like, there are DNS records, they’re stored on a server, what’s the big deal? But with DNS, reading about how it works in a textbook doesn’t prepare you for the sheer volume of different ways DNS can break your system in practice. It’s not just caching problems!...

5d

How to find a domain's authoritative nameservers

Here’s a very quick “how to” post on how to find your domain’s authoritative nameserver. I’m writing this because if you made a DNS update and it didn’t work, there are 2 options: Your authoritative nameserver doesn’t have the correct record Your authoritative nameserver does have the correct record, but an old record is cached and you need...

2w

Why might you run your own DNS server?

One of the things that makes DNS difficult to understand is that it’s decentralized. There are thousands (maybe hundreds of thousands? I don’t know!) of authoritative nameservers, and at least 10 million resolvers. And they’re running lots of different software! All these different servers running software means that there’s a lot of inconsistency...

3w

2021: Year in review

It’s the end of the year again! This was my second full year working for myself on wizard zines. Here are some thoughts about what I’m working towards, a bunch of things I made this year, and a few ideas and questions about 2022. made some progress on a “mission statement” I think the two hardest things about working for myself are working...

3w

New tool: Mess with DNS!

Hello! I’ve been thinking about how to explain DNS a bunch in the last year. I like to learn in a very hands-on way. And so when I write a zine, I often close the zine by saying something like “… and the best way to learn more about this is to play around and experiment!“. So I built a site where you can do experiments with DNS called Mess With...

Dec 2021

DNS doesn't "propagate"

Hello! Yesterday I tweeted this: I feel like the term "DNS propagation" is misleading, like you're not actually waiting for DNS records to "propagate", you're waiting for cached records to expire— 🔎Julia Evans🔍 (@b0rk) December 5, 2021 and I want to talk about it a little more. This came up because I was showing a friend a demo of how DNS caching...

Dec 2021

How to use dig

Hello! I talked to a couple of friends recently who mentioned they wished they knew how to use dig to make DNS queries, so here’s a quick blog post about it. When I first started using dig I found it a bit intimidating – there are so many options! I’m going to leave out most of dig’s options in this post and just talk about the ones I actually...

Dec 2021

Debugging a weird 'file not found' error

Yesterday I ran into a weird error where I ran a program and got the error “file not found” even though the program I was running existed. It’s something I’ve run into before, but every time I’m very surprised and confused by it (what do you MEAN file not found, the file is RIGHT THERE???!!??) So let’s talk about what happened and why! the...

Nov 2021

Some notes on using esbuild

Hello! I’ve been writing more frontend code in the last year or two – I’ve been making a bunch of little Vue projects. (for example nginx playground, sql playground, this dns lookup tool, and a couple of others) My general approach to frontend development has been pretty “pretend it’s 2005” – I usually have an index.html file, a script.js file,...

Nov 2021

How do you tell if a problem is caused by DNS?

I was looking into problems people were having with DNS a few months ago and I noticed one common theme – a lot of people have server issues (“my server is down! or it’s slow!“), but they can’t tell if the problem is caused by DNS or not. So here are a few tools I use to tell if a problem I’m having is caused by DNS, as well as a few DNS debuggging...

Nov 2021