After attaching an Auto Scaling group to an ELB, you notice that new instances are launched but do not receive any traffic. What is the most probable cause?

medium📝 Debug Q6 of 15

AWS - Auto Scaling

AThe Auto Scaling group has exceeded its maximum size limit.

BThe instances have not passed the ELB health checks and are not yet registered as healthy targets.

CThe ELB is configured to use TCP listeners instead of HTTP listeners.

DThe instances are launched in a different AWS region than the ELB.

Step-by-Step Solution

Solution:

Step 1: Check instance health status
Instances must pass ELB health checks to receive traffic.
Step 2: Understand traffic routing
ELB routes traffic only to healthy registered instances.
Final Answer:
Instances have not passed ELB health checks and are not yet healthy targets. -> Option B
Quick Check:
Unhealthy instances do not get traffic [OK]

Quick Trick: Instances must be healthy in ELB to receive traffic [OK]

Common Mistakes:

Confusing max size limit with traffic routing
Assuming listener protocol affects instance registration
Ignoring region mismatch as a cause

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More AWS Quizzes

After attaching an Auto Scaling group to an ELB, you notice that new instances are launched but do not receive any traffic. What is the most probable cause?

Step 1: Check instance health status

Step 2: Understand traffic routing

Final Answer:

Quick Check:

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