Quick Answer
The answer is to use an UpdateReplacePolicy of 'Replace'. This is correct because the UpdateReplacePolicy attribute in CloudFormation dictates what happens when a resource must be physically replaced during a stack update; setting it to 'Replace' ensures CloudFormation creates the new Lambda function with the updated code before deleting the old one, achieving a zero-downtime code update. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of CloudFormation's resource lifecycle policies, often appearing in scenarios involving stateful or critical resources like Lambda behind API Gateway. A common trap is confusing UpdateReplacePolicy with DeletionPolicy—remember that UpdateReplacePolicy governs replacement behavior during updates, not deletion. For a quick memory tip: think "Replace first, then delete" to avoid downtime.
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.
A company uses AWS CloudFormation to deploy a microservices architecture. The Operations team needs to update a stack that contains a Lambda function and an API Gateway REST API. They want to ensure that the Lambda function code is updated without downtime. Which update policy should be used for the Lambda function in the CloudFormation template?
Use an UpdateReplacePolicy of 'Snapshot'
Why wrong: Snapshot is not a valid update policy for Lambda.
Use an UpdateReplacePolicy of 'Replace'
Replace will create a new Lambda function and then delete the old one, allowing for an update.
Use an UpdateReplacePolicy of 'Retain'
Why wrong: Retain keeps the old resource and does not apply updates.
Use an UpdateReplacePolicy of 'Rollback'
Why wrong: Rollback is not a valid update policy.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use an UpdateReplacePolicy of 'Replace'
The correct answer is B because the `UpdateReplacePolicy` attribute in CloudFormation is used to specify the behavior when a resource must be replaced during a stack update. Setting it to `Replace` ensures that the Lambda function is recreated with the new code, and because CloudFormation creates the new function before deleting the old one (for Lambda), there is no downtime. This policy directly addresses the requirement for a zero-downtime code update.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Use an UpdateReplacePolicy of 'Snapshot'
Why it's wrong here
Snapshot is not a valid update policy for Lambda.
Use an UpdateReplacePolicy of 'Replace'
Why this is correct
Replace will create a new Lambda function and then delete the old one, allowing for an update.
Related concept
Read the scenario before looking for a memorised answer.
Use an UpdateReplacePolicy of 'Retain'
Why it's wrong here
Retain keeps the old resource and does not apply updates.
Use an UpdateReplacePolicy of 'Rollback'
Why it's wrong here
Rollback is not a valid update policy.
Common exam traps
The trap here is that candidates confuse `UpdateReplacePolicy` with `DeletionPolicy` or assume that `Retain` is safe for updates, but `Retain` only applies to deletion and would cause the update to fail because the old resource is not replaced.
Detailed technical explanation
Under the hood, when CloudFormation replaces a Lambda function with `UpdateReplacePolicy: Replace`, it creates the new function first, updates the API Gateway integration to point to the new function's ARN, and then deletes the old function. This is possible because Lambda function ARNs are immutable and CloudFormation can manage the transition atomically. A real-world scenario where this matters is during a blue/green deployment of a microservice, where the API Gateway must not serve 5xx errors during the switchover.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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FAQ
Configuration Management and IaC — This question tests Configuration Management and IaC — Read the scenario before looking for a memorised answer..
The correct answer is: Use an UpdateReplacePolicy of 'Replace' — The correct answer is B because the `UpdateReplacePolicy` attribute in CloudFormation is used to specify the behavior when a resource must be replaced during a stack update. Setting it to `Replace` ensures that the Lambda function is recreated with the new code, and because CloudFormation creates the new function before deleting the old one (for Lambda), there is no downtime. This policy directly addresses the requirement for a zero-downtime code update.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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