Free Practice Questions for Amazon Web Services DVA-C02 Exam

Requirement Summary:

WebSocket-based messaging app usingAPI Gateway WebSocket APIs

Need to:

Identify clients repeatedlyconnecting/disconnecting

Be able toremoveproblematic clients

Evaluate Options:

A. Switch to HTTP APIs

❌HTTP APIs don’t supportWebSocketconnections

B. Switch to REST APIs

❌REST APIs arenot compatiblewith WebSockets

✅C. Use the callback URL to disconnect clients

⚠️Possible, butnot a direct option

Callback URLs are used forsending messages to connected clients, not for disconnecting

✅D. Track client status in ElastiCache

✅Good solution: Store and update connection state (connected, disconnected, timestamps)

Helpstrack abuse or reconnections

✅E. Implement $connect and $disconnect routes

✅Required to captureconnection lifecycle events

These can be used to log/store client behavior and decide on removal

WebSocket routes in API Gateway:https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-websocket-api-route-selection.html

Managing WebSocket connections:https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-websocket-api-mapping-template-reference.html

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and consistent performance with seamless scalability. The developer can store each employee’s contact information in a DynamoDB table along with the object keys for the photos stored in Amazon S3. Amazon S3 is an object storage service that offers industry-leading scalability, data availability, security, and performance. The developer can use AWS APIs to search and retrieve the employee details and photos from DynamoDB and S3.

AWS Elastic Beanstalk supports several deployment policies, and in this case, the requirement is to forward a specific percentage of traffic to the new version without causing downtime. TheTraffic-splittingdeployment policy is the most appropriate choice.

Traffic-splitting Deployment: This deployment method allows you to gradually shift a specified percentage of incoming traffic from the old environment version to the new one. During the evaluation period, if any issues are detected, the traffic can be redirected back to the old version.

No Downtime: This method ensures no downtime since both versions of the application run concurrently, and traffic is split between them.

Alternatives:

Rolling deployments (Option A): These gradually replace instances but may result in partial downtime if some instances fail during deployment.

In-place deployments (Option C): In-place deployments replace instances without creating new ones, which can lead to downtime.

Immutable deployments (Option D): While this ensures no downtime by creating entirely new instances, it doesn't provide traffic splitting during the evaluation phase.

Requirement Summary:

NLP Lambda function with alarge pre-trained model

Lambda layer became8.7 GB→ Exceeds AWS limits

Function returns RequestEntityTooLargeException

Need:High-performing,portable, lowinitialization time

Important AWS Limits:

Lambda Layers size limit(combined across all layers):250 MB (unzipped)

Deployment package size(unzipped):250 MB

Lambdacontainer image supportallows up to10 GBimage size

Evaluate Options:

A: Store model in S3 and load during execution

❌Leads tocold start latencyevery time

Model loading from S3 isslowerand not suitable for real-time NLP

Not optimal for performance

B: Use EFS mounted to Lambda

⚠️Valid for large models, butadds latencyduring cold start as model loads from EFS

Requires EFS setup, VPC, and has addednetwork I/O overhead

Still slower than bundling in container image

C: Split into five Lambda layers

❌Still violates thetotal layer size limitof 250 MB (unzipped)

You cannot exceed that even with multiple layers

✅D: Use Docker container image

✅Allows bundlingup to 10 GBof dependencies and models

✅Highportabilityandperformance

✅Avoids latency of downloading models at runtime

✅Ideal for scientific/NLP models

Lambda container image support:https://docs.aws.amazon.com/lambda/latest/dg/images-create.html

Lambda limits:https://docs.aws.amazon.com/lambda/latest/dg/gettingstarted-limits.html

Using large models with Lambda:https://aws.amazon.com/blogs/machine-learning/deploying-large-machine-learning-models-on-aws-lambda-with-container-images/

This is a frequent trouble. Web applications cannot access the resources in other domains by default, except some exceptions. You must configure CORS on the resources to be accessed.https://docs.aws.amazon.com/AmazonS3/latest/userguide/cors.html

The response from the API call indicates that the ProvisionedThroughputExceededException exception has occurred. This exception means that the rate of incoming requests exceeds the throughput limit for one or more shards in a stream. To mitigate this exception, the developer can use one or more of the following techniques:

Implement retries with exponential backoff. This will introduce randomness in the retry intervals and avoid overwhelming the shards with retries.

Reduce the frequency and/or size of the requests. This will reduce the load on the shards and avoid throttling errors.

Increase the number of shards in the stream. This will increase the throughput capacity of the stream and accommodate higher request rates.

Use a PutRecord API instead of PutRecords. This will reduce the number of records per request and avoid exceeding the payload limit.

Requirement Summary:

Secrets managed inAWS Secrets Manager

DB:Amazon RDS for PostgreSQL

Needautomated password rotation

Must maintainhigh availability

Least development effort

Rotation Strategies:

✅Single-user rotation strategy

✅Simplest to implement

The secret containsone set of credentialsused by app and rotation logic

✅Supportsautomated rotation

AWS providesbuilt-in Lambda rotation templatesfor RDS

A. Alternating-users strategy

⚠️More complex

Requires application toswitch usersduring rotation window

B. Manual secret + CLI rotation

❌Too much manual work

Not scalable or reliable

C. Multivalue answer rotation

❌Not a valid strategy in this context

Doesn’t apply to Secrets Manager

Secrets Manager rotation strategies:https://docs.aws.amazon.com/secretsmanager/latest/userguide/rotating-secrets.html

RDS PostgreSQL secret rotation:https://docs.aws.amazon.com/secretsmanager/latest/userguide/rotating-secrets_strategies.html#rotating-secrets-single-user

The solution that will meet the requirements is to add a new stage to the pipeline. Use AWS CodeBuild as the provider. Add the new stage before the stage that deploys code revisions to the test environment. Write a buildspec that fails the CodeBuild stage if any test does not pass. Use the test reports feature of CodeBuild to integrate the report with the CodeBuild console. View the test results in CodeBuild. Resolve any issues. This way, the developer can run the unit tests automatically during the CI/CD process and catch any bugs before deploying to the test environment. The developer can also use the test reports feature of CodeBuild to view and analyze the test results in a graphical interface. The other options either involve running the tests manually, running them after deployment, or using a different provider that requires additional configuration and integration.