Application Load Balancer target limitations

Question

We're approaching our holiday sales peak in a couple of weeks and we have an application that requires over 1500 instances on a target group. This target group is attached an application load balancer.

Looking at AWS docs, it states that the target group can have more than 1,000 targets and this is adjustable. We can increase it.

https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-limits.html

> Targets per Target Group per Region (instances or IP addresses) ---> 1,000 and adjustable

However, the load balancers section states that:

> Number of times a target can be registered per Application Load Balancer --> 1000 and not adjustable

This seems ambiguous to me. So, can we have more than 1,000 targets per target group that are attached to an application load balancer?

Riku_Kobayashi · Answer

Hello.

For NLB, the number of targets can be set to 1000 or more.  
I think that's why the number of targets in a target group can be adjusted.    
In other words, for ALB you can't go above 1000, so I don't think you can set up more than 1000 instances even if you increase the target group quota.  
https://docs.aws.amazon.com/elasticloadbalancing/latest/network/load-balancer-limits.html

Kallu · Answer

> Number of times a target can be registered per Application Load Balancer = 1000

This is saying you can register the same target (instance or IP address) up to 1000 times with single ALB. Remember that you register a tupple of ID/IP and PORT. This limit can not be changed, but 1000 ports on single instance should be plenty for common use-cases.

Application Load Balancer target limitations

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