There’s a definitive answer to this question, and you can find it in RFC 8375: use
home.arpa. Never heard of it before? It wasn’t assigned as a special purpose top-level domain (spTLD) name for residential and small networks until 2018.
home.arpa spTLD isn’t a globally unique domain name, and you can’t resolve it across the internet. It’s only meant to be used inside a small network, such as your home network. Routers and DNS servers know, [in theory,] not to forward ARPA requests they don’t understand onto the public internet.
Just something I found interesting. When I get my server up I might try to send all my DNS do it and I’ll be able to do all sorts of fun things. That said I think
home.arpa is a terrible TLD. looks ugly. Da heck is arpa(1) in this context? Advanced Research Projects Agency (ARPA)?? But who doesn’t love following standards right?
(1): as per RFC 3172 it’s actually Address and Routing Parameter Area