DNS doesn't "propagate"

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2021-12-06 18:30:06

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

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

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 works last week, and he realized that what was happening in the demo didn’t line up with his mental model of how DNS worked. He immediately brought this up and adjusted his mental model (“oh, DNS records are pulled, not pushed!“). But this it got me thinking – why did my very smart and experienced friend have an inaccurate mental model for how DNS works in the first place?

First – I’m very tired of posts that complain about how people are “wrong” about how a given piece of technology works without explaining why it’s helpful to be “right”. So here’s why I like knowing how DNS works.