[mrtg] MRTG and DynDNS

[Alex van den Bogaerdt]

On Tue, Sep 04, 2007 at 02:38:22PM +0800, Guenther Boelter wrote:

> I have an agent/client with a dynamic IP address using dyndns.org. At
> the moment the IP address for the client has changed MRTG can't get
> datas anymore from that client because MRTG is still using the old ip.

Is MRTG, or is your entire system?

Perhaps you've just found out about DNS caching...

http://en.wikipedia.org/wiki/Domain_name_system#Caching_and_time_to_live

I'm not saying that it certainly is not mrtg, I don't know, but I
could think about a couple of other places where things could go wrong.

I hope someone else can give a more definitive answer but in the mean
time you could try to narrow down the problem area.  Some tools will
use the DNS resolver (and return cached data) some will bypass it and
return the new IP address.  Maybe a small perl program would do, one
pinging the host one time and thus showing the IP address.

HTH
Alex