The answer is to update the alias to point to the previous version. This is correct because AWS Lambda aliases are immutable pointers that decouple the invocation endpoint from the actual function version; by simply reassigning the alias, you instantly revert all traffic to the stable code without any redeployment or code changes. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of Lambda versioning and alias routing as a safe, zero-downtime rollback mechanism—a common trap is thinking you need to delete the new version or redeploy the old one, which is unnecessary and slower. Remember the memory tip: "Alias is the steering wheel, versions are the gears—just turn the wheel to go back, don't rebuild the engine."
DVA-C02 Deployment Practice Question
This DVA-C02 practice question tests your understanding of deployment. 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 developer deploys a new version of an AWS Lambda function using the AWS CLI. After the deployment, the function starts returning errors. The developer needs to quickly revert to the previous version without redeploying. What should the developer do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Update the alias to point to the previous version.
Option B is correct because AWS Lambda aliases are immutable pointers to specific function versions. By updating the alias to point to the previous version, the developer can instantly revert traffic to the stable code without any redeployment, as the alias is used as the invocation target (e.g., via the function's ARN with the alias name). This approach leverages Lambda's built-in versioning and alias routing, which is the fastest and safest rollback mechanism.
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.
✗
Use AWS CodeDeploy to automatically roll back the deployment.
Why it's wrong here
CodeDeploy is used for automated deployments, not for a simple manual rollback in this scenario.
✓
Update the alias to point to the previous version.
Why this is correct
Updating the alias to point to the previous version provides an instant rollback.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the AWS CLI to update the function code with the previous code.
Why it's wrong here
This would redeploy the code but is not the fastest rollback method.
✗
Delete the current function and recreate it using the previous deployment package.
Why it's wrong here
Deleting and recreating is time-consuming and error-prone.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think they need to redeploy or use a separate deployment service (like CodeDeploy) to revert, when in fact Lambda's alias and versioning system provides a built-in, instant rollback mechanism without any code changes.
Trap categories for this question
Scenario analysis trap
CodeDeploy is used for automated deployments, not for a simple manual rollback in this scenario.
Detailed technical explanation
How to think about this question
Lambda versions are immutable snapshots of function code and configuration, each with a unique ARN (e.g., arn:aws:lambda:us-east-1:123456789012:function:my-function:1). An alias (e.g., 'prod') points to a specific version and can be updated atomically via the AWS CLI command `aws lambda update-alias --function-name my-function --name prod --function-version 1`. This operation is instantaneous and does not require any code upload or deployment, making it ideal for rapid rollbacks in production.
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
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
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.
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Update the alias to point to the previous version. — Option B is correct because AWS Lambda aliases are immutable pointers to specific function versions. By updating the alias to point to the previous version, the developer can instantly revert traffic to the stable code without any redeployment, as the alias is used as the invocation target (e.g., via the function's ARN with the alias name). This approach leverages Lambda's built-in versioning and alias routing, which is the fastest and safest rollback mechanism.
What should I do if I get this DVA-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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Question Discussion
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