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 # testipRalph Mitchell