Thoughts while building

For OpenFreeMap, I'm using servers behind Round Robin DNS. In this article, I'm trying to understand how browsers and CDNs select which one to use.

Normally, when you are serving a website from a VPS like Digital Ocean or Hetzner, you add a single A record in your DNS provider's control panel.

This allows you to share the load between multiple servers, as well as to automatically detect which servers are offline and choose the online ones.

It's an amazingly simple and elegant solution that avoids using Load Balancers. It's also free, and you can do it on any DNS provider, whereas Load Balancing solutions can get really expensive (even on Cloudflare, which is otherwise very reasonably priced).

I became obsessed with how it works. I mean, on the surface, everything is elegant, but how does a browser decide which server to connect to?

In theory, there is an RFC 8305 called Happy Eyeballs (also linking to RFC 6724) about how the client should sort addresses before connecting.

Leave a Comment