DNS-level solutions are oftentimes misunderstood, probably because there are a couple of things that can be done at this level: 1. "Geo-DNS" is about using an

DNS-level solutions are oftentimes misunderstood, probably because there are a couple of things that can be done at this level: 1. "Geo-DNS" is about using an anycast network to direct users to their nearest datacenter(s). This does _not_ aid High Availability at all. 2. DNS Round Robin is about distributing the load between multiple IPs. As a load balancing solution it is relatively poor, because you have no control over the actual balancing and can end up receiving most users though a single IP. 3. DNS Failover solutions that replace the IP when the server goes down, which is also a poor solution because of TTL and non-TTL browser caches. 4. DNS Round Robin but for the High Availability, not for the balancing. This is actually an interesting approach because most modern browsers automatically switch to using (one of) the other record(s) when the IP they were using goes down (sorry, I have no reference that clearly states which browser do and which ones don't exhibit this behavior). In fact, there are some sources around [1] that seem to identify this approach as the only one to achieve instant failover in the face of datacenter-wide outages. [1] http://serverfault.com/questions/69870/multiple-data-centers-and-http-traffic-dns-round-robin-is-the-only-way-to-assur http://serverfault.com/questions/69870/multiple-data-centers...