[dns-operations] co-operative cacheing

[Paul Vixie]

> I was thinking of using a local broadcast to perform the cluster lookaside
> (though you'd need a way of deciding who gets to reply), perhaps in
> parallel with the normal query so that it doesn't affect latency.

i think a local broadcast isn't practical for most topologies whose recursive
nameservers are geographically diverse.  and there's no parallel to the web
proxy data sharing case you mentioned -- ICP (RFC 2186) and HTCP (RFC 2756)
are directed point to point protocols.

however, doing a short-short-timeout nonrecursive probe of another recursive
nameserver in parallel with launching an upstream query might work out.  the
complexity here isn't interoperability or new protocols, but rather, resolver
internal state.  i'll try this out locally and report back my results.