What is likely causing this issue?

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In: DOP-C01
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With: 1 Comment
A company recently launched an application that is more popular than expected.The company wants to ensure the application can scale to meet increasing demands and provide reliability using multiple Availability Zones (AZs).The application runs on a fleet of Amazon EC2 instances behind an Application LoadBalancer (ALB).A DevOps engineer has created an Auto Scaling group across multiple AZs for the application.Instances launched in the newly added AZs are not receiving any traffic for the application.

What is likely causing this issue?

Auto Scaling groups can create new instances in a single AZ only.

The EC2 instances have not been manually associated to the ALB.

The ALB should be replaced with a Network Load Balancer (NLB).

The new AZ has not been added to the ALB.

Explanations:

Auto Scaling groups can create instances across multiple AZs if the AZs are enabled in the group configuration.

EC2 instances should automatically register with the ALB when launched in an Auto Scaling group, provided the correct target group is configured.

A Network Load Balancer (NLB) is typically used for different use cases, such as low latency and high throughput. An ALB is sufficient for scaling and handling traffic across multiple AZs.

If the new AZ is not added to the ALB, instances in that AZ will not be registered with the load balancer, and thus won’t receive traffic.

2025-10-03

1 Comment

  1. Sarah
    Author

    I think the answer is:
    The new AZ has not been added to the ALB.

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