Split-Horizon DNS at Home: One Domain, Two Answers

Thu, 01 Feb 2024 13:38:00 +0000

Here’s a problem that arrives the moment you self-host something with a proper hostname. You’ve got a service at nextcloud.mylab.local, or better still at cloud.example.com using a real certificate, and you want to reach it both from your sofa and from a train. From the train the name has to resolve to your public IP so traffic can find its way in through the router. From the sofa, resolving to the public IP means your packets go out to the internet and try to come straight back in — a manoeuvre called NAT hairpinning that many home routers do badly or refuse to do at all. The clean answer is to give the same name two different addresses depending on who’s asking. That is split-horizon DNS, and once you understand why you want it, the how is short.

Split-Horizon - vo.rs

Split-Horizon DNS at Home: One Domain, Two Answers