On Thu, Nov 3, 2011 at 6:44 PM, Darrik Mazey <user-634f30452b72@xymon.invalid>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