Logging question.

Kevin Darcy kcd at daimlerchrysler.com
Thu Jun 15 21:48:49 UTC 2000


MexiAce wrote:

> I am running a couple of DNS servers (Bind 8).  We use Keynote for web
> perfomance statistics to our site.  I am seeing a number of DNS lookup
> errors in the report.  What kind of logging can I enable that will tell me
> if the DNS servers are being over-utilized and can't handle the load, or if
> there is another reason that we are seeing the DNS lookup errors.  I am
> assuming at this point that the number of DNS lookup errors are very small
> compared to the successful lookups because of the amount of web traffic to
> our site.

If capacity is your main concern, then the statistics facility of BIND is
probably the most useful thing to look at initially. By default, named dumps
some statistics to syslog every hour (both the destination of the statistics
data, and the frequency, are configurable).

But, what are these "lookup errors"? Timeout errors may indicate a capacity
problem (or possibly a networking problem), but other kinds of errors probably
point more to configuration problems. Additionally, what some software
describes as DNS "errors" just simply means that a particular name doesn't
exist, or that some remote server not under your control is misconfigured or
having a problem, i.e. these "errors" may not indicate any problems with
*your* DNS infrastructure at all. Before potentially going off on a wild goose
chase, I'd probably want more information on the nature of the "errors" that
the application is reporting.

If they are real errors, then increasing your logging, or possibly even
turning on debugging, may be necessary to determine the cause. But be aware
that debugging output can be quite voluminous, and the learning curve for
interpreting named's debugging output is rather steep.


- Kevin





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