Re: difference in dnscache installs

richard lucassen <[email protected]>
Newsgroups gmane.network.djbdns
Organization XAQ Systems
Message-ID <[email protected]>
On Tue, 19 Jan 2010 19:49:07 -0500
[email protected] (Paul Jarc) wrote:

> > This sounds very logical. But OTOH DJB would have build this in as a
> > variable, wouldn't he?
> 
> It's MAXUDP, a macro defined in dnscache.c.  It's not designed to be
> configurable, because raising it significantly above 200 would cause
> strange problems on some platforms.  It might work for yours, though.
> It depends on how many file descriptors your system's select() or
> poll() function can handle.

Ik increased MAXUDP to 300, but no results. And just to exclude that
there are some external causes involved, I set up an extra instance of
dnscache on 127.53.3.1 and did the same query:

$ time host www.singaporeair.com 127.53.3.1
www.singaporeair.com    CNAME   www.singaporeair.com.edgekey.net
www.singaporeair.com.edgekey.net        CNAME
www.singaporeair1.akadns.net www.singaporeair1.akadns.net    CNAME
e449.b.akamaiedge.net e449.b.akamaiedge.net   A       88.221.185.237

real    0m5.908s
user    0m0.004s
sys     0m0.000s

So it definitely must be the load of dnscache that make these
CNAME-hell lookups fail.

Do you guys have another hint what can be done? There are two instances
of dnscache running on two different machines. The CACHELIMIT/DATALIMIT
is set to 100MB. The two machines have the same problem. A quick scan of
the logs shows some 1300 lookups per minute, thats around 20 per second.
No further problems are reported, just these CNAME-hell lookups don't
work. I have seen this problem before ever since these nameservers have
been running (ever since 1.05 came out) and I resolved this issue by
adding these entries to the local tinydns. But the last few weeks there
were more and more errors reported, that's why I'd like to find another
solution for this problem.

R.

-- 
___________________________________________________________________
It is better to remain silent and be thought a fool, than to speak
aloud and remove all doubt.

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| Richard Lucassen, Utrecht                                        |
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