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My ELB logs shows 2 ip addresses which means requests are being balanced from two nodes: "The IP address of the load balancer node that handled the request."

My console shows 1 ELB in 2 availability zones. Does that mean that there is one node for each AZ?

lf215
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    Where specifically are you seeing this? Please include some CLI output or other specific wording from the console, or a screenshot. – Matt Houser Mar 09 '17 at 03:41
  • More specifically: elb adds a new log file for every 5 minutes. In my case there are two log files every 5 minutes. So they come in pairs. In the pair, one file name has ip X and the other has ip Y. The file name is quite long but it follows the syntax that is discussed in the link I included. – lf215 Mar 09 '17 at 03:44
  • Can you be more specific about "My console shows 1 ELB in 2 availability zones." ? – Matt Houser Mar 09 '17 at 04:03
  • The load balancer id part of all the log file names is `a-b-c`. When I go to the load balancer section in the console there is one result for load balancer with name "a-b-c". That single row shows "us-east-1e, us-east-1c" in the Availability Zones column. – lf215 Mar 09 '17 at 04:09

1 Answers1

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When the AWS Management Console shows you that ELB a-b-c is in multiple availability zones, like us-east-1e, us-east-1c, that means that your ELB is listening in those availability zones. So your clients will be split up among the ELB nodes in those zones.

If your ELB is in 2 zones, then your ELB has atleast 2 nodes. But depending on your scaling and number of back-end EC2 instances, your ELB may have more than 2 nodes: there may be multiple nodes in each AZ.

Matt Houser
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    Also good to keep in mind that, by default, an ELB will spread the load evenly between the zones. So you need about the same number of web servers in each zone. If you have 10 servers in one zone and 2 in another, the 2 will get pounded. More info here: http://docs.aws.amazon.com/elasticloadbalancing/latest/classic/enable-disable-crosszone-lb.html. – systemjack Mar 09 '17 at 07:44