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List:       linux-ha
Subject:    re: keep it simple high-availabilty
From:       Greg Freemyer <freemyer () NorcrossGroup ! com>
Date:       2002-07-30 16:10:42
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 >>  Just some thoughts about high-availability - what you can do if you don't
 >>  need shared storage or if you have two cheap Internetconnections that you
 >>  want failover for services on.

 >>  One way to do it is could be to run a nameserver on each host that also is
 >>  running the webserver, but let the nameservers have different information
 >>  in their zones. So that every nameserver tell their clients that the
 >>  webserver is located on the same server as it self. And use a very low
 >>  TTL.

 >>  This has probably been done before, but since I hadn't heard of this
 >>  particular idea, well, I thought it couldn't hurt to let somebody know.

 >>  Here is a webpage describing it:

 >>  http://jerker.nyberg.org/kisha.html

 >>  Regards,
 >>  Jerker Nyberg.
 >>  Uppsala, Sweden.

Jerker

I did not read your full write-up, but anyone considering very short TTLs in =
their DNS server should know that not all DNS cache servers on the web honor =
them.

In particular, a year or so ago, AOL would only honor TTLs of 24 hours or =
greater.  I don't know about now.

So, to use a short TTL based solution, you have to have a captive audience that =
you can ensure will honor your TTL requests.

Greg Freemyer
Internet Engineer
Deployment and Integration Specialist
Compaq ASE - Tru64 v4, v5
Compaq Master ASE - SAN Architect
The Norcross Group
www.NorcrossGroup.com
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