Cisco Distributed Director

Kevin Darcy kcd at daimlerchrysler.com
Fri Jun 16 22:05:45 UTC 2000


I still don't get it. BIND 4.9.7 implemented *true* round-robin, so the load
should be split as equally as possible for DNS-based load-balancing. Could
it be that the low TTL is *causing* some sort of skewing? I seem to recall
that BIND 4 didn't deal very well with 0 TTL's.

Have you tried it with a *higher* TTL value? I know it seems rather
paradoxical...

Regardless, you should upgrade.


- Kevin

Dan Considine wrote:

> Here's the environment.
>
> Primary DNS server (Bind 4.9.7 / Solaris 2.6)
> Secondary DNS server (Bind 4.9.7 / Solaris 2.6)
>
> Distributed Director (Cisco IOS 11.1.(20)IA)
>
> I have delegated dd.us.ml.com from my DNS servers to
> the DD
>
> dd.us.ml.com IN NS  wfddd1.ml.com
>    IN NS  huddd1.ml.com
>
> On the DD I have a director host setup with 8 ip's with
> equal portion metrics,  TTL = zero
>
> wfdbbsocks-p.dd.us.ml.com (8 ip addresses)
>
> Clients have the following:
>
> Primary and Secondary DNS servers setup as their resolvers.
>
> Start Openbloomberg, config file states wfdbbsocks-p.dd.us.ml.com
> as it's socks server.
>
> Client tries to resolve socks server by way of resolvers,  resolvers
> go to the DD (wfddd1 or huddd1) to get an A record,  DD returns an ip
> by way of equal portion metrics (round robin),  resolver returns ip
> to client and caches this A record with a TTL of zero.  Now,  this is
> fine on a client by client query,  works fine.  The problem is when we
> restart our proxy servers.  We have 3,000 users connected over the 8
> machines,  once the client loses it's connection it tries to get another
> ip.  So,  we have 3,000 queries sent to DNS,  DNS starts handing out the
> last cached ip while it tries to get another 1 from the DD, by this time
> it's too late,  maybe 500 clients already received the same ip which
> defeats
> the round robin setup.  I need to find a way to have our DNS servers send
> the client to the DD for the A record (non-recursive dns).
>
> Dan Considine wrote:
>
> > Is there a way to setup non-recursion on an NS record in Bind 4.9.7?  I
> > need to have client queries sent to my Distributed Director for
> > resolution,  TTL on the Director is set to "0",  root server takes 1
> > second to cache this record which
> > defeats the purpose of the "0" TTL.    Any ideas?
> >
> > Thanks in advance,
> >
> > Dan.






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