I've been wondering about the effects of stub resolvers with caches as clients of recursive servers. To what extent do they cause a thundering herd effect where all the cache entries expire with the same deadline? The herd will arrive when the RRset expires so most of those clients will hit maximum latency and stress the server's query deduplication mechanism.
(I don't think I have enough traffic to get a useful answer from my servers right now.) If thundering herds happen, do they thunder enough to help explain the lack of benefit from prefetching observed by PowerDNS? Or maybe is the herd is too small to thunder? Instead there's a more gentle swell of queries after the TTL expires? https://lists.dns-oarc.net/pipermail/dns-operations/2019-April/018605.html If there is much of a herd, would it make sense to give some proportion of the clients a slightly reduced TTL so that they will trigger prefetch before the rest of them requery? Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ Bailey: Southwest 4 or 5, increasing 6 or 7 later. Moderate or rough, occasionally very rough later in far northwest. Drizzle, fog patches. Moderate or poor, occasionally very poor. _______________________________________________ dns-operations mailing list [email protected] https://lists.dns-oarc.net/mailman/listinfo/dns-operations
