> If I recall correctly, so far *every* Linux I've used uses an external
> DNS by default instead of installing its own recursor.
>
> I figure there must be a reason, but I don't know what it is.

So a cache becomes more efficient if several machines use it -
especially given the branching/hierarchical structure of DNS.
But that was in the good old days - thesedays with intrusive
monitoring, it might be worthwhile to run a local DNS cache
for the privacy benefit and take the hit of a bit more back
and forth - modern client machines have enough resources to
run it

I believe some distributions already use things like dnsmasq
to do simpler caching, and I remember that a while ago
libc offered a caching daemon (nscd ? nsdc ?) for anything
in nsswitch.conf although I think the API there didn't allow for
some of the subtleties that DNS offers

Actually it might even even be worth investigating alternate
NS implementations - maybe somebody knows of a proof-of-work
libnss_* library ? Something like that might decentralise
things even more ...

I suppose the latter are pie in the sky ideas - getting a
useful release out is more important, but maybe work for
later...

regards

marc