same. saved my ass already a few times when doing some reverseengineering voodoo. being able to set a valid https cert makes it easier to redirect apps than to bypass forced HTTPS. had to pretend to be a update server for something once and patching the URL was enough via getting a cert quickly (using DNS-01 challenge, no exposed ports ever)
I actually use .lan for an internal domain but I guess I could use a real domain with the DNS-01 challenge and have real internal certificates. I had not thought about that until just now.
According to IETF, you should only use .intranet, .internal, .private, .corp, .home or .lan for your private network ( RFC 6762 Appendix G ). Using other TLDs might cause issues in the future, especially since new gTLDs seems to show up every few months or so, which can collide with the TLD you use for your local network.
A problem with the .lan TLD (maybe others from this list) is that web browsers do not consider it a TLD when you type it in the address bar, and only show you the option to search for that term in your default search engine. You have to explicitly type https:// before it, to have the option to visit the URL.
E.g type example.com in the address bar -> pressing Enter triggers going to https://example.com. Type example.lan -> pressing Enter triggers a search for example.lan using your default search engine.
Little known trick--or perhaps everyone knows it and is quietly laughing behind my back--with Chromium browsers and Firefox (and maybe Safari, I'm not sure), you can add a slash to the end of an address and it will bypass the search.
So, for example, my router on the LAN goes by the hostname "pfsense". I can then type pfsense.lan/ into my address bar and it will bring me to the web UI, no HTTP/s needed.
A long time ago Microsoft and some teaching sources used .local in example documentation for local domains and it stuck. Like contoso.com was Microsoft's example company. I was taught to use .local decades ago and it took a very long time to unlearn it.
Same here. I have several domains, one is used for servers and email, 2nd for websites, 3rd for messing around (test setups) and a 4th is almost unused now, but with the demise of twitter and reddit I'm thinking of using that one for the fediverse (it's my username in national tld).
BTW internal and external dns run on different systems and all private zones are dnssec signed. (Loved the challenge on setting that up correctly)
For local DNS home.arpa is I think what we're 'supposed' to use, but I use .lan
Only use another domain name if you actually have it registered, like myname.net or something. As a bonus you can then get a wildcard letsencrypt SSL cert for easy HTTPS.
Because of interference with existing domains. Say you set a computer on your network to mypc.google.com, that won't work because the DNS server will lookup google.com as an external domain.
fritz.box for the machines themselves because Fritz!BOX (although handed out by Pi-Hole),but .lan for anything going over the local proxy towards the same machine for TLS.
Some machines use my custom domain name instead of .lan, if they need to be accessible from outside. So these last ones go directly over the local proxy internally, but automatically over CloudFlare Tunnel and Authentik when not at home. The proxy being Caddy.
I didn't care about any of this (my off the shelf Router used .local) and then I started selfhosting more and using pFsense as a router OS. It defaulted to using home.arpa, which was so objectionable that I spent time looking into RFC 6762 and promptly reverted to .lan forever.
The official choices were: .intranet, .internal, .home, .lan, .corp, and .private. LAN was the shortest and most applicable. Choice made.
I use different ones. Got an legit dpmain which I also use locally (with ssl certificates) and in my local network my server listens to SERVI. Just SERVI.
While this works for most things, you will run into issues with certain software which automatically assume that no TLD means the provided address is incorrect.