Help with Cisco Distributed Director and DNS subdomain

Barry Margolin barmar at bbnplanet.com
Fri Oct 15 14:47:38 UTC 1999


In article <199910150417.AAA06300 at fw1-a.osis.gov>,
Joseph S D Yao  <jsdy at cospo.osis.gov> wrote:
>No experience, but ... why don't you just try following the
>instructions?  No zone transfers needed.  Just put the above lines into
>your "my.domain.com" zone file.  Every time someone wants the address
>for http-proxy, they find that they have to ask the DD which - if it is
>properly configured - will distribute the load in that manner.  And I
>am sure the TTL of the names is QUITE low.  ;-)

I do have experience, and everything Joe said is correct.

In fact, in my experience, the TTL of the names is *too* low.  The default
is 0, to prevent any caching.  But some nameservers seem to have a problem
with 0 TTL's (some ancient versions of BIND, as well as some current
non-BIND servers (miraculously, I don't think MS DNS suffers from this)).
I recommend configuring the DD to use TTL something like 10 seconds or 1
minute.  There isn't really much point to going lower than this, since the
DD only recalculates its tables once a minute by default, most internet
topology doesn't change that often, and many client applications do their
own caching that may last even longer (I think Netscape defaults to 5
minutes).

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.


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