Re: Core dumps & restarting

Rob Hagopian (
Wed, 6 Nov 1996 14:44:19 -0500 (EST)

> Hmm.. just a crazy thought.. What if you were to have 2 machines with
> the same IP, on the same subnet, but have only one of them send
> _anything_ back in response. The 2 machines would have identical
> hardware, and an identical installation. If all connections to the
> master (the one that will respond) were duplicated on the secondary, which
> made no attempt to respond at the physical layer in any way. Then the
> secondary would naturally operate identically.
> Note that all the applications and services would think they were the
> ones responding on the secondary, and it works only because the 2
> machines are identical in every way.
> A udp "heartbeat" (stolen from a previous message :) ) could be used to
> let the secondary take over the connections if the primary stopped.
> Hopefully I have described my idea well enough for you to understand it,
> and I'm sure it'd have some problems, but I just thought I'd share it
> with you anyway :)

A big problem with this is that things aren't always the same. Just for
example, what if you were running a program that generated a random number and
then used that to encrypt all data between the hosts from then on. Unless both
machines picked the same number, only the first machine would be able to talk
to the client. As much as it would be nice, computers aren't quite that
predictable yet.
-Rob Hagopian