[acranox]

I know all that. IMHO in that configuration the root servers are your upstream servers. That’s what I was trying to convey. And serving expired records does generally work, but is not suggested practice.

[icedchai]

Technically, you don't have upstream DNS servers in that configuration. The root servers are not recursive resolvers like an upstream.

But this isn't a problem... DNS caching works very well. I've been running my own nameservers for over two decades.

[acranox]

potato potato