[dredmorbius]

Actually, the local address of your Pi-Hole server, though that's configurable.

https://docs.pi-hole.net/ftldns/blockingmode/

For hosts files, 0.0.0.0 is generally preferred, which marks the host as unreachable, rather than localhost (127.0.0.1, etc.), which might well recieve and try to process the request.

https://serverfault.com/a/300410

[Mister_Snuggles]

Neat! I'm going to have to play with that a bit.

I'm using the defaults, but from the sounds of the documentation having it return 0.0.0.0 might be beneficial. It certainly explains some weirdness that I've seen when using Pi-Hole.

Thanks!