BIND BOTTLENECK: internall 90 seconds query timeout & recursive-clients limit

[Barry Margolin]

In article <c8btnt$73u$1 at sf1.isc.org>,
 Ladislav Vobr <lvobr at ies.etisalat.ae> wrote:

> well I am reposting this, since I didn't get any reply last time, not
> even a single one:-(, and honestly I don't expect many this time, since
> as I have noticed isc support became commercial, and post by person
> directly from isc team in this 'still free mailing list' has become so
> rare since that time....
> 
> ....perhaps even this list should become commercial and people should
> get paid for reporting and many times even solving/patching things in
> this list..
> 
> from isc.org site about the commercial 3rd line support...
> 
> ...." A certification process is being defined to ensure ISC is
> providing 3rd line support and not general help desk questions."...
> 
> will this list be considered now for "general help desk questions" ?
> 
> I personally think bind is great product and isc.org great company, but
> feeling sad from the selective approach perhaps isc is going to acquire
> now, about what should be answered for free and what is going to be "3rd
> line support" and people in the mailing list will never see it, correct
> me if I am wrong

This list is not for technical support from ISC.  The people who answer 
in this list are mostly not associated with ISC at all, we're just 
knowledgeable users.

ISC is not a commercial software vendor.  If you want to purchase 
technical support, go to Nominum, Inc. <www.nominum.com>.

> 
> ..............................
> My questions below
> ..............................
> 
> When all the nameservers for certain domain are unreachable, bind
> doesn't log or bogus such a servers or domain, be it unreachable even
> for hours/days/weeks/years. Administrator has no idea how many such
> servers are being permanently retried in the background from his server
> for hours/days/weeks/years. He can discovered it only by chance or
> waiting for the customer complain, to trigger the troubleshooting.
> 
> worse of this, imho if the internal timeout of each such a query is 90
> seconds, 11 such queries to unreachable domains per seconds are enough
> to fill the default 1000 concurrent recursive query queue after these 90
> seconds only by these type of requests.

What's the chance that so many queries for unreachable domains will 
happen simultaneously?  I don't think I've ever seen a server get stuck 
like this, and our caching servers at Genuity were very heavily used.

I think this will actually only be a problem if *all* the servers for a 
domain are down.  BIND keeps track of past response times for servers, 
and chooses the one with the best previous response time when selecting 
which NS record for a domain to use.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***