DVA-C02 Question #258: Real Exam Question with Answer & Explanation

Question

A developer is building a serverless application by using AWS Serverless Application Model (AWS SAM) on multiple AWS Lambda functions. When the application is deployed, the developer wants to shift 10% of the traffic to the new deployment of the application for the first 10 minutes after deployment. If there are no issues, all traffic must switch over to the new version. Which change to the AWS SAM template will meet these requirements?

Options

• ASet the Deployment Preference Type to Canary10Percent10Minutes. Set the AutoPublishAlias
• BSet the Deployment Preference Type to Linear10PercentEvery10Minutes. Set AutoPublishAlias
• CSet the Deployment Preference Type to Canary10Percent10Minutes. Set the PreTraffic and
• DSet the Deployment Preference Type to Linear10PercentEvery10Minutes. Set PreTraffic and

Explanation

The Canary10Percent10Minutes deployment preference type shifts exactly 10% of traffic to the new Lambda version for 10 minutes, then shifts all remaining traffic if no alarms fire.

Common mistakes.

• B. Linear10PercentEvery10Minutes shifts an additional 10% every 10 minutes incrementally until 100% is reached, which would take 100 minutes total. This does not match the requirement of shifting all traffic after just 10 minutes.
• C. PreTraffic and PostTraffic hooks are used for running validation Lambda functions before and after deployment, not for configuring the traffic shift percentage or timing. They are optional and not required to meet this requirement.
• D. Linear10PercentEvery10Minutes does not meet the timing requirement, and PreTraffic/PostTraffic hooks do not control the traffic shift schedule.

Concept tested. AWS SAM canary deployment preference for Lambda traffic shifting

Reference. https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/automating-updates-to-serverless-apps.html

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