When we ran into UDP tuning issues on high traffic devices it presented as silent discards rather than SERVFAIL.
On Thu, Sep 27, 2018, 12:04 PM Alex <mysqlstud...@gmail.com> wrote: > Hi, > > > On Thu, Sep 27, 2018 at 10:53:25AM -0400, Alex wrote: > > > Many of these values I've already tweaked and have had no effect on my > > > SERVFAIL issues :-( > > > > If you are getting SERVFAILs from a BIND resolver you administer, then > > it has responded to your query. If you turn up the log level to > > something like -d 99, it'll print the steps that led to that SERVFAIL. > > Usually you'll find something there that directs you to next steps. > > > > On this topic, my home resolver is also a stock packaged BIND version as > > you, and I too see spurious SERVFAILs sometimes. I used to think this > > was due to too much indirection, e.g., when named starts up and you run: > > > > dig -x 176.9.81.50 > > It doesn't typically happen when running from the command-line. It > does occasionally happen, though. I usually run something like "dig > +all +trace +nodnssec <hostname>". It sometimes times out in the > middle, with something like "cannot resolve xyz host", which may even > be one of the root servers. > > I also typically run it with "rndc trace 11" which shows me quite a > bit of debugging info - too much to look through manually. With trace > 99, I can imagine it being overwhelming amount of info. Do you have > any ideas of what to look for? "query-errors"? > > Also, I also see other SERVFAIL errors that really are SERVFAIL errors > - when querying the host manually, it still responds immediately with > SERVFAIL. > > Thanks, > Alex > > > > > > > on a cold cache. However it seems to be returning SERVFAIL sometimes for > > what should be a cached answer. I'll also turn up the debug logging and > > watch it. > > > > Mukund > _______________________________________________ > 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 >
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