Dynamic DNS issue

Kevin Darcy kcd at daimlerchrysler.com
Tue Jan 4 00:56:20 UTC 2005

Daniel Rudy wrote:

>This is more of a how-to question than anything else.  Basically, I have
>two consumer xDSL lines at different locations that I want to be able to
>have the computers find each other.  The DSL lines are PPPoE with
>dynamicly assigned IP addresses.  The only thing that is constant is the
>hostnames which are registered with a dynamic DNS service and are
>available across the internet.
>Now my question is how to I setup the servers at each location so that
>they update each other's DNS information?
I guess I don't quite understand your question. If both boxes register 
themselves in DNS, and Machine A can resolve the IP address of Machine B 
by its name, and _vice_versa_, then why do you need to do anything more?

If the propagation time for the changes is intolerably long, I suppose 
you could run a couple of local caching nameserver/resolver instances on 
each box, one with a low max-cache-ttl, e.g. on the order of seconds, or 
a low number of minutes, in order to keep things dynamic, with the other 
instance selectively forwarding to it (selectively, because you wouldn't 
want _everything_ you look up to be that dynamic). Note that I've never 
actually tried such a setup, but it should work in theory. You might 
want to first check with the dynamic DNS service to ensure that they 
don't have a problem with you -- and everyone else with the same idea -- 
hammering their nameservers like that.

Or, alternatively, just bite the bullet and get static IPs.

- Kevin

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