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I'm just set up a small load balanced architecture in AWS using two Large EC2 instances in the same availability zone with a non-sticky ELB in front. Amazon reports that both instances are health and I see the healthchecks returning 200 on both servers, yet all traffic is being routed to one of the servers. If I pull that server out of rotation traffic goes to the other server, but when I put it back in it all goes back to that one server. This is live traffic - not a load test - so its not related to single-client-IP or sticky sessions.

Any suggestions for what I can look at or how to begin to debug the elastic load balancer setup? Thanks

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I'm going to assume your backends are (were as this is old) in different AZs and you had a limited set of clients which were caching DNS or you were using an A record for the ELB. – Nathan V Sep 8 '15 at 22:15

Is there a stickiness policy for the ELB? Check in the AWS Console, EC2 > Load Balancers > [your ELB] > Description. Under Port Configuration it should say "Stickiness: Disabled".

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Stickyness is no longer an option in AWS console... – CMag Oct 17 '12 at 15:53
I still see it is present in the documentation… and in the AWS console. – dialt0ne Oct 17 '12 at 17:37

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