Yup -- they most certainly do. I think they switch around the name -> IP mapping in response to traffic rates -- if you suddenly get a surge of traffic, they'll move your virtual ELB instance to a physical load balancer that is currently lightly loaded.
Basically, they are doing load balancing for their load balancers. :)
Does this actually cause a disruption of service though? It seems like it would be trivial to just keep the configuration in place for 72 hours even after changing the DNS entry.
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Does the IP of the AWS load balancers ever change over time? Does anyone know the technical reasoning behind the requirement?
Yup -- they most certainly do. I think they switch around the name -> IP mapping in response to traffic rates -- if you suddenly get a surge of traffic, they'll move your virtual ELB instance to a physical load balancer that is currently lightly loaded.
Basically, they are doing load balancing for their load balancers. :)
Does this actually cause a disruption of service though? It seems like it would be trivial to just keep the configuration in place for 72 hours even after changing the DNS entry.
They actually do that -- they keep the old IP live for a while to prevent problems with clients that might have cached the IP.
So could we not update the A records IP address every couple of hours and still get roughly speaking the benefit of load-balanced load-balancers?