I had an interesting challenge in work recently, we have 3 data centres running our applications, currently the RR DNS system does what it’s supposed to, spreads the data round each of the 3 DCs evenly. This works fine when all of your data centres have a similar capacity. But ours don’t. This causes problem when your load/traffic gets to the point where one of the DCs can’t cope. Now, there are many expensive and complicated solutions to this, this how ever isn’t one of them, it’s quite simple, has it’s weaknesses, but as you’ll see it’s also quite elegant.