What domain name to use for your home network?

Adding for completeness sake one can ignore this if they run their own DNS at home and add their custom local domain as private. An example of telling Unbound DNS that a domain is local [1]:

    private-domain: "hotmess"
    local-data: "my.hotmess. 1d IN A 10.10.10.10"
    local-data-ptr: "10.10.10.10 1d my.hotmess."
    local-zone: "use-application-dns.net." always_nxdomain

    dig my.hotmess
    my.hotmess.  86400 IN A 10.10.10.10
    ;; Query time: 0 msec

The potential side-effect would be that DoH hosts that do not query "use-application-dns.net" or ignore it will not be able to resolve this. There are pros and cons to this and one must judge for themselves if this is acceptable. As a side note, if people wish to reduce the load on the root servers then consider running your own DNS server and also tuning every OS and DNS library to prefer either ipv4 or ipv6 first, whichever one makes the most requests for and remove search domains. This alone can cut out over 30% of all DNS requests.

[1] - https://unbound.docs.nlnetlabs.nl/en/latest/manpages/unbound...