> Beyond that, there are some obvious tradeoffs. Unless your DNS cache is > 100% compute bound, if a few extra local hashes avoid upstream queries, it > is likely to be an overall performance win.
John, have you ever heard of "livelock"? I think you are thinking about this in terms of per-query performance, but caches that handle large amount of traffic do not measure performance per query: they measure performance at a particular query load. This means that although any given query is never CPU bound, when figuring out how many DNS cache servers you are going to have to install, you still very definitely need to account for CPU utilization. Unless you simply aren't seeing any significant query load, you figure out what your steady-state query load is, and you figure out what your maximum query load is, and you figure out from that how many servers you need to deploy. If you triple the per-query CPU load, then you need to buy three times as many servers. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
