Question 1,713 of 1,740
Configuration Management and IaChardMultiple SelectObjective-mapped

Quick Answer

The answer is to define a lifecycle hook for the Auto Scaling group that delays instance termination until the new instance is fully registered and healthy with the load balancer. This works because the lifecycle hook pauses the termination of the old instance during a rolling update, giving the new instance time to pass the Application Load Balancer’s health checks and begin receiving traffic before the old one is removed. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of how to orchestrate zero-downtime CloudFormation updates for Auto Scaling behind an ALB, often paired with an UpdateWaitCondition to signal CloudFormation to proceed only after healthy registration. A common trap is assuming that simply updating the launch configuration or using a shorter health check interval alone prevents downtime, but without the lifecycle hook, the old instance can be terminated before the new one is ready, causing a gap in service. Memory tip: think “hook before you cook” — the lifecycle hook keeps the old instance “on the hook” until the new one is fully cooked and serving traffic.

DOP-C02 Configuration Management and IaC Practice Question

This DOP-C02 practice question tests your understanding of configuration management and iac. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Which THREE actions should be taken to ensure that an AWS CloudFormation stack update does not cause downtime for a production application that runs on an Auto Scaling group behind an Application Load Balancer? (Select THREE.)

Question 1hardmulti select
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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

Configure an 'UpdateWaitCondition' in the CloudFormation template to pause the stack update until a healthy signal is received from the new instances.

Option A is correct because an 'UpdateWaitCondition' in a CloudFormation template can pause the stack update until a healthy signal is received from the new instances. This ensures that the update proceeds only after the new instances have passed health checks, preventing premature traffic routing and potential downtime.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Configure an 'UpdateWaitCondition' in the CloudFormation template to pause the stack update until a healthy signal is received from the new instances.

    Why this is correct

    Wait conditions allow you to verify that new instances are healthy before proceeding.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Add a custom resource that triggers an AWS Lambda function to take a snapshot of the database before the update.

    Why it's wrong here

    Database snapshotting is not directly related to application downtime during a stack update.

  • Ensure that the Auto Scaling group spans at least three Availability Zones to distribute instances.

    Why it's wrong here

    Multiple AZs improve fault tolerance but do not directly control update behavior.

  • Set the Auto Scaling group's UpdatePolicy to 'AutoScalingRollingUpdate' with a 'BatchSize' of 1 and 'MinInstancesInService' equal to the desired capacity.

    Why this is correct

    This ensures only one instance is replaced at a time, maintaining capacity.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Define a lifecycle hook for the Auto Scaling group that delays instance termination until the new instance is fully registered and healthy with the load balancer.

    Why this is correct

    Lifecycle hooks allow you to perform custom actions before termination, ensuring no traffic loss.

    Related concept

    Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may confuse general high-availability practices (like multi-AZ distribution) with specific update-time actions that prevent downtime, or they may think database snapshots are relevant to instance-level availability during a stack update.

Detailed technical explanation

How to think about this question

The 'AutoScalingRollingUpdate' policy with 'BatchSize' of 1 and 'MinInstancesInService' equal to desired capacity ensures that only one instance is replaced at a time, and the desired number of instances remain in service throughout the update. Lifecycle hooks, combined with a 'CONTINUE' or 'ABANDON' action, can delay instance termination until the new instance is fully registered and healthy with the ALB, preventing traffic gaps. Under the hood, CloudFormation uses the Auto Scaling group's health check grace period and ELB health checks to coordinate the rolling update, and lifecycle hooks integrate with Amazon SNS or SQS to signal completion.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this DOP-C02 question test?

Configuration Management and IaC — This question tests Configuration Management and IaC — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Configure an 'UpdateWaitCondition' in the CloudFormation template to pause the stack update until a healthy signal is received from the new instances. — Option A is correct because an 'UpdateWaitCondition' in a CloudFormation template can pause the stack update until a healthy signal is received from the new instances. This ensures that the update proceeds only after the new instances have passed health checks, preventing premature traffic routing and potential downtime.

What should I do if I get this DOP-C02 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 24, 2026

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This DOP-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 DOP-C02 exam.