On Mar 18, 2016, at 6:28 AM, Barry Margolin <bar...@alum.mit.edu> wrote: > In article <mailman.384.1458255932.73610.bind-us...@lists.isc.org>, > Mark Andrews <ma...@isc.org> wrote: > >> How do you actually expect this to ever work in real life? > > I'm pretty sure Google DNS does this. Other resolver operators often get > complaints about "Why can't I look up <whatever> through your DNS > servers when I can do it through Google DNS?"
I’d guessed Google just re-queries before it needs to, which has benefits but requires a more complex “clean out very-seldom-used records” strategy. I’d imagine they'd use a somewhat-random amount of time to pre-query as one of their measures against cache poisoning. This would be a good nameserver feature, e.g. when a response is given from the cache, a secret (shorter) ttl is adjusted to help assure continuity. Or other variants. Such a feature might address Ron’s concern. (I believe I recall discussions on this or another list, perhaps even a feature in the wings.) In any case, I cringe at the thought of overriding TTLs. They’re there for a reason. In some instances, overriding could “help”, but in others, it would be really, really bad. John Wobus Cornell University IT _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
