Tuning for survey workloads

[Viktor Dukhovni]

My workload sends lots of queries to various TLDs and public suffix
2LDs (.co.uk, ...), but non-infrastructure queries to leaf domains
are almost not repeated sufficiently often to be found in the cache.

How should I tune the cache?  Ideally, (but unbound likely can't
do this), the NS/A/AAAA/DNSKEY records of domains that have delegated
sub-domains would be cached in a separate cache (maybe even a
separate max-ttl) from the cache that handles "leaf" domains.

In the mean time I probably need a medium-sized infra cache and a
small data cache?  Not quite sure how to tune a nameserver whose
dominant client walks ~6 or more million domains scattered across
various TLDs and 2LDs, getting a few records from each domain
(DNSKEY, MX, A + TLSA for each MX stopping early if same MX already
seen at some other domain or is in an unsigned zone) and moves on
to the next domain, visiting each delegated domain "once" (a few
related queries in quick succession, in parallel with a few hundred
similar domains).

As mentioned originally, 3.5 billion queries, 1.4 million cache
hits!  Any advice on tuning for "surveys"?

-- 
	Viktor.