[Xymon] Listening on Multiple IPs

[Ralph Mitchell]

On Thu, Nov 3, 2011 at 6:44 PM, Darrik Mazey <darrik.lists at darmasoft.com>wrote:

> On 11/03/2011 03:57 PM, Xymon User in Richmond wrote:
> > DNS will return all 3 IPs on a query, and it's left to the client side
> > which to use.  Most often the first one is used.  "Round robin" DNS
> > servers will alternate the order of the 3, but that still leaves a lot of
> > room for locking in on a single address by multiple clients.  You could
> > set up different names for the IPs and bind groups of Xymon clients to
> > each to spread out the load, I think.
>
> This will also depend on whether the xymon client resolves the ip once
> at startup or on each data send.  If it's once at startup, then whatever
> ip it is given (even from a round-robin dns server) will persist until
> it is restarted.  I'll leave it to those who have examined this behavior
> and xymon client internals to say which is the case.


 If I recall past conversations correctly, xymon goes out to resolve
hostnames every time.  However, the actual behaviour depends on the host
system - if the host is running a name server cache daemon (e.g. nscd),
then xymon will be handed whatever is cached until that expires, then it'll
get a fresh copy from the real DNS.

You can override the name lookup for any given hostname by putting "testip"
on it's line in server/etc/hosts.cfg:

    1.2.3.4 xxx.thingy.com     # testip


Ralph Mitchell
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