AIUI both Mac OS X and Solaris have a caching non-recursive resolver,
so for example when you change DNS records, even if you are pointed
with resolv.conf to another server your client will not pick up the
changes until you type 'svcadm restart name-service-cache' or
'dnscacheutil -flushcache' to clear the old data. NetBSD obviously
hasn't got a caching resolver---I wonder if growing such a thing is
needed for good-neighbor transparent mDNS, or is everything you need
in the mDNSResponder server part.