SAP-C02 ALB Health Checks Practice Question
A company runs a production application on EC2 instances behind an Application Load Balancer. After a recent deployment, users report intermittent 503 errors. The CloudWatch metrics show that the ALB's 'TargetResponseTime' is within normal range, but 'RequestCount' has increased by 50%. There are no changes to the security groups. What is the MOST likely cause of the 503 errors?
⚠ Common exam trap
Candidates may confuse 503 errors with timeout or capacity issues. In this scenario, the normal TargetResponseTime and increased RequestCount suggest the load balancer is working, but targets are being marked unhealthy due to a missing health check path.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The deployment removed the health check path from the application.
If the deployment removed the health check path from the application, the health checks would fail for any instance that was updated. Since the application runs behind an ALB, the target group health check would mark those instances as unhealthy, causing intermittent 503 errors as traffic is routed only to remaining healthy instances. Even if not all instances are updated simultaneously, the gradual roll-out could lead to periods where all instances become unhealthy temporarily. Option A is incorrect because a low idle timeout would cause timeout errors, not 503s. Option B is incorrect because security groups were not changed. Option C is incorrect because misconfigured health check settings would cause consistent failures, not intermittent.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The ALB's idle timeout is set too low.
Why it's wrong here
Low idle timeout would cause connection resets, not 503 errors.
- ✗
The security group for the ALB does not allow inbound traffic on the listener port.
Why it's wrong here
Security group was not changed, and if it were blocking traffic, all requests would fail.
- ✗
The ALB's target group health check settings are misconfigured.
Why it's wrong here
Health check misconfiguration would cause persistent failures, not intermittent errors.
- ✓
The deployment removed the health check path from the application.
Why this is correct
If the health check path is removed, health checks fail, causing targets to be marked unhealthy, and ALB returns 503.
Go deeper
Related to this question
About these practice questions
Courseiva writes every SAP-C02 question from scratch — 1,660 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAP-C02 exam.