On 11/07/2013 03:52 PM, Edward Lewis wrote: > > In experimenting with some recursive servers (and by no means an > exhaustive set), some code bases did adhere to the "rules" and some code > bases seem to ignore the "rules." I say this to the extent that the > collective set of deployed tools out there pretty much are eating into > the "longer TTLs will reduce queries" part of the above trade-off. >
...which would give you only the drawbacks and not the upside... Not answering your question what a good value is (...it depends, but apparently what it depends on may be something different than we thought), but I do have one immediate question: Did you see specific points at which TTLs are no longer adhered to? (e.h. do resolvers out there cap TTL values and if so, do they set it to said cap or reduce it to a fixed value, or does it appear completely random)? TBH I don't think it's very important to the pre-fetch discussion itself; some tools will play nice and use the sane pre-fetch values (like pre-fetch only if queries in the last few seconds of a TTL), and some tools will be tools and not play nice no matter what. I don't think it adds a lot of extra uncertainty, as long as prefetchers don't go into the area of 'always fetch at 50% of TTL'. OTOH if all bets are off anyway, adding some more unpredictability wouldn't hurt ;) Jelte _______________________________________________ dns-operations mailing list dns-operations@lists.dns-oarc.net https://lists.dns-oarc.net/mailman/listinfo/dns-operations dns-jobs mailing list https://lists.dns-oarc.net/mailman/listinfo/dns-jobs
