So I recently got pisession kf a nas with OMV on it. That has a webinterface that I can reach from my laptoo via "openmediavault.local". But I never defined anywhere that that adress leads to the IP of my server. Better still, if I restart my server an DHCP gives it a new IP, "openemdiavault.local" still works.

How does that work? And can I make an andress like "radar.local" that automatically points to my radarr webinterface no matter hwat it's IP is?

https://en.wikipedia.org/wiki/Multicast_DNS

And can I make an andress like "radar.local"

I think you also need a reverse proxy for this to work, so your NAS knows that radarr.local has to redirect to Radarr's port. I use nginx-proxy-manager and it feels nice and easy to use.

And can I make an andress like "radar.local" that automatically points to my radarr webinterface no matter hwat it's IP is?

https://gitlab.isc.org/isc-projects/kea has a dyndns module. I use it as part of opnsense.

This works for services with their own IP address. If you run multiple docker containers on the same docker host, but you want to give each docker service its own name: http(s) reverse proxy.

I assume that your browser computer is set up to use mDNS, and that's how it's resolving it.

https://en.wikipedia.org/wiki/Multicast_DNS

Multicast DNS (mDNS) is a computer networking protocol that resolves hostnames to IP addresses within small networks that do not include a local name server. It is a zero-configuration service, using essentially the same programming interfaces, packet formats and operating semantics as unicast Domain Name System (DNS). It was designed to work as either a stand-alone protocol or compatible with standard DNS servers.[1]

mDNS uses IP multicast and User Datagram Protocol (UDP) packets and is implemented by Apple, Microsoft and most Linux distributions.

mDNS can work in conjunction with DNS Service Discovery (DNS-SD), a companion zero-configuration networking technique specified separately in RFC 6763.[2]

By default, mDNS exclusively resolves hostnames ending with the .local top-level domain.

Your browser tries to resolve it, browser computer sends out a multicast query to the local network, target "openmediavault" machine responds.

Your open media vault claims a name and your router makes it available by its name dot local.

Other services will get the same treatment if they use a name. On my network about a third use a name.

This thread has pointed me to multicast dns, I assume that's what you mean. Do you know of an easy way to have your service claim such a name?

It's just regular LAN DNS behind a masquerading router. Inside your network services can get names in a few ways

1. A hosts file mapping IP address to a name placed on any machine that wants to use names. Downsides: not automatic, hard to update in a dynamic DNS environment. Works fine if you assign every service a static address (my printer always gets 192.168.1.5, for example — configured in the router(

2. Have the service respond to a DNS offer with "thanks, my name is fileserver" and the router can resolve fileserver.local to 192.168.0.203

I use host files and my addresses below 192.168.1.100 are reserved for static addresses and my half dozen things I want to address by name get one of those addresses