Why bother with the load balancer? I am curious, I am sure there is a reason, but it isn't making a lot of sense to me. You can either do round robin dns, or just pass out the 3 read server addy's to the clients for failover (and change the order for real poor mans load balancing.)
Things DNS RR does not allow that a load balancer does (just off the top of my head): 1. Dynamically removing a node if it goes down/crashes (DNS RR slows things down because clients need to time out for a failed server, assuming clients do properly time out and fail over, which is not a guarantee by any means - lots of broken clients wrt DNS RR out there). 2. Easily removing a node for maintenance (DNS RR requires modifying DNS, waiting for TTLs, hoping none of the clients ignore TTLs - again, lots of broken clients out there, etc). 3. Can't account for differing load or connection levels to backend servers. 4. Hiding the actual servers and/or number of servers in the cluster.
I'm sure there are other benefits I'vve forgotten.