Ignoring domain xxxxxxxxx.yyy for DHCP host name zzzzzzzzzz

Anything? How is rebind protection on my router going to be applicable to the issue I'm seeing?

On another note...
Looking through this thread, I see mention of editing:

/etc/dnsmasq.d/99-domains.conf

Is this do-able from within the Pi-hole web GUI? In my case, Pi-hole is running in a Docker container (from Pi-hole), and as best I can tell I don't have access to edit any files within its locked container. The only apparent access is through the application UI.