BIND and UDP tuning

[Mukund Sivaraman]

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

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