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?" > Caches will generally have expired / not learnt the records by the > time you realise that you want to keep records longer so there is > no point even coding support for this into caches. We don't have > time machines. Of course, if the record hasn't been cached in the first place, there's nothing you can do. But a heavily-used resolver will quickly cache most popular records. When a cached record expires, the server should try to refresh it. If it gets a valid response, it updates the cache. But providing the old record if there's no response is not an unreasonable approach to fault tolerance. It would be reasonable to have a configured maximum lifetime for these expired records, so that caches wouldn't fill up with lots of detritus from abandoned domains. A day seems like long enough for the authoritative server operator to fix their problem. -- Barry Margolin Arlington, MA _______________________________________________ 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
