Development with AWS Services

A developer has an AWS Lambda function that processes messages from an Amazon SQS queue. The function is configured with a batch size of 10, reserved concurrency of 5, and a timeout of 5 minutes. The SQS queue has a large backlog, and CloudWatch metrics show high throttling (Throttles) for the Lambda function. The function is idempotent and can process up to 100 messages in a single invocation. What is the MOST effective way to increase throughput without increasing the reserved concurrency?

A developer has an AWS Lambda function that processes messages from an Amazon SQS standard queue. The function is idempotent and currently has a batch size of 10. The developer wants to increase throughput and increases the batch size to 100. After the change, CloudWatch metrics show a significant increase in throttles and the queue backlog is growing. The function's reserved concurrency is set to 10. What is the most effective action to resolve the throttling and improve throughput?

A developer is using AWS X-Ray to trace a serverless application. The application uses an AWS Lambda function to query a DynamoDB table. The trace shows that the DynamoDB subsegment takes a significant portion of the total response time. The developer wants to reduce the DynamoDB query latency. Which service should the developer integrate with the Lambda function to achieve the lowest latency for repeated read queries?

A developer is building a serverless application using AWS Step Functions to orchestrate multiple AWS Lambda functions. One of the Lambda functions occasionally fails due to a transient error. The developer wants the Step Functions execution to automatically retry the failed task up to three times with exponential backoff. Which configuration should the developer set in the Step Functions state machine definition?

A developer is building a serverless application that processes orders. An order is placed and an event is published to an Amazon SNS topic. The SNS topic has multiple subscribers, including an SQS queue for order processing and a Lambda function for sending notifications. The developer wants to ensure that the SQS queue receives all messages reliably, even if the processing Lambda function fails temporarily. Which configuration should the developer set?

A developer is building a REST API using Amazon API Gateway and AWS Lambda. The API receives a large number of requests with duplicate payloads from the same client within a short time window. To reduce Lambda invocations and improve performance, the developer wants to return the previously computed response for identical requests based on a unique client ID in the header. How can the developer achieve this using API Gateway features?

A developer is building a RESTful API using Amazon API Gateway (HTTP API) and AWS Lambda. The API receives a large number of requests with duplicate payloads within a short time window. To improve performance and reduce costs, the developer wants to ensure that if the same request (based on a unique client ID) is sent within 5 minutes, the Lambda function is not invoked again, and the previously calculated response is returned. Which API Gateway feature should the developer use?

A developer is building a RESTful API using Amazon API Gateway and AWS Lambda. The API needs to support custom domain names with SSL/TLS certificates. The developer has created the custom domain name in API Gateway and uploaded the certificate to AWS Certificate Manager (ACM) in the same region. However, when accessing the custom domain, users get an SSL error. What is the most likely cause?

A developer is building a system that reads messages from an Amazon SQS queue, processes them, and stores results in an Amazon DynamoDB table. The developer wants to use a managed service to coordinate the processing steps, including error handling and retry logic, without provisioning any servers. Which AWS service should the developer use?

A developer is building a serverless application using AWS Lambda and Amazon API Gateway. The API must support different HTTP methods (GET, POST, PUT, DELETE) for the same resource path. The developer wants to define the API in a single Lambda function that can handle all methods without additional mapping configuration. Which Lambda integration type should the developer use?

A developer is building a serverless application that processes user-submitted images. The images are uploaded to an S3 bucket, which triggers an AWS Lambda function that creates a thumbnail and stores it in another S3 bucket. The developer notices that sometimes the Lambda function is invoked multiple times for a single image upload. What should the developer configure to ensure idempotent processing?

A developer is building a serverless application that uses an Amazon SQS FIFO queue to process orders. The orders must be processed exactly once and in the order they are received. The developer uses an AWS Lambda function as the consumer. Despite using a FIFO queue, the developer notices that some orders are being processed more than once. What is the most likely cause of this behavior?

A developer is building a multi-region application using Amazon DynamoDB global tables. The application needs to read data from a replica table in a different region shortly after a write in the primary region. The developer notices that reads sometimes return stale data. Which of the following explains this behavior?

A developer is migrating a monolithic application to a microservices architecture on AWS. The application uses a relational database. The developer wants to use Amazon RDS for the database and needs to ensure that each microservice can only access its own set of tables. Which approach should the developer take?

A developer is running a web application on multiple Amazon EC2 instances behind an Application Load Balancer (ALB). The application needs to store user session state that must be available across all instances. The session data is small and temporary but must survive individual instance failures. Which AWS service should the developer use to store this session state?

A developer is building a web application that uses Amazon DynamoDB as the database. The application needs to store user session data and must support eventual consistency reads for most use cases, but strongly consistent reads for critical operations. The developer wants to minimize costs. Which read capacity unit (RCU) configuration should the developer use?

A developer is building a serverless application using AWS SAM. The application includes an Amazon API Gateway endpoint with a Lambda function that processes user uploads. The developer wants to enable API caching in the development stage to speed up repeated requests, but disable caching in the production stage. What is the most efficient way to achieve this?

A developer is building a serverless application using AWS Lambda and Amazon DynamoDB. The application needs to store large JSON documents (up to 1 MB) and retrieve them by a primary key. The documents are updated frequently. Which DynamoDB feature should the developer consider to optimize performance and cost for storing and retrieving these large items?

A developer is building a serverless application using AWS Step Functions. The workflow must execute hundreds of thousands of short-lived tasks per day, each taking less than 30 seconds. The tasks need to run in parallel, and a small number of duplicate executions are acceptable. Which type of Step Functions workflow should the developer choose?

A developer is using the AWS Serverless Application Model (SAM) to define a serverless application with an API Gateway endpoint. The developer wants to enable API caching only in the development stage to speed up testing, but disable it in the production stage to ensure data freshness. What is the most efficient way to achieve this with SAM?

A developer is building a serverless application using AWS SAM that includes an API Gateway REST API and a Lambda function. The developer wants to pass environment variables to the Lambda function based on the deployment stage (dev/prod). The stage name is provided as a SAM parameter. How should the developer define this in the SAM template?

A developer is building a RESTful API that allows clients to query a database and retrieve results. The backend logic is implemented in AWS Lambda, which queries an Amazon DynamoDB table. The developer wants to expose the API over HTTPS and manage authentication and throttling. Which AWS service should the developer use to create and manage the API endpoints?

A developer is building a serverless application that uses Amazon S3 event notifications to trigger an AWS Lambda function for thumbnail generation. The developer wants to ensure that duplicate S3 events do not cause the same image to be processed multiple times. Which approach should the developer implement to ensure idempotent processing?

A developer configures an AWS Lambda function to process image files uploaded to an S3 bucket. The bucket receives a mix of .jpg, .png, and .pdf files. To reduce costs, the developer wants the Lambda function to be invoked only for image files (.jpg and .png). How should the developer configure the S3 event notification?

A developer is building a serverless application that needs to store user session data. The data is small (a few KB per user) and must be accessible across multiple invocations of the same Lambda function and across different Lambda functions. The session data should persist for the duration of the user session (up to 1 hour). Which storage solution should the developer use?

A developer wants to update an AWS CloudFormation stack that includes an Amazon SQS queue. The queue is currently processing messages. The developer needs to change the queue's default visibility timeout without losing any messages. Which approach should the developer take?

A developer is implementing an e-commerce application where a purchase operation must deduct inventory and create an order atomically. The inventory and orders are stored in separate DynamoDB tables. Which DynamoDB feature should the developer use to execute these operations as a single, all-or-nothing transaction?

A developer is building a serverless application using AWS Lambda and Amazon API Gateway. The API requires that the same Lambda function handle different HTTP methods (GET, POST, DELETE) for the same resource. The developer wants to minimize code and configuration. Which integration type should the developer use?

An application running on Amazon EC2 instances behind an Application Load Balancer (ALB) intermittently returns 503 errors. The ALB health checks are failing for some instances intermittently. The developer checks the instance system logs and finds no application errors. What is the most likely cause of the health check failures?

A company is building a RESTful API using Amazon API Gateway and AWS Lambda. The API must allow users to authenticate using an identity provider that supports OpenID Connect (OIDC). The developer wants to offload authentication and authorization to API Gateway. Which API Gateway feature should the developer use?

A developer is creating a REST API using Amazon API Gateway with Lambda proxy integration. The API needs to accept and return binary data such as images or PDF files. The developer has configured the API to use the Lambda proxy integration. What additional configuration is required to support binary data?

A developer is building a REST API using Amazon API Gateway that will serve static content from an Amazon S3 bucket. The API should cache responses for frequently accessed objects to reduce latency. Which API Gateway feature should the developer enable?

A developer is building a serverless application using AWS SAM. The application includes a Lambda function that needs read-only access to an S3 bucket. The developer wants to use SAM's built-in policy templates to grant this permission. Which policy template should be used in the SAM template?

A developer is building a REST API using Amazon API Gateway and AWS Lambda. The API must support request validation, request throttling, and API keys. Which API Gateway feature should the developer use to enforce a daily request limit for each API key?

A developer is creating a REST API using Amazon API Gateway and multiple AWS Lambda functions for different endpoints. The API must support CORS for a web application hosted on a different domain. The developer is using Lambda proxy integration. Which configuration is required to enable CORS?

A developer is building a microservices application composed of multiple AWS Lambda functions and an Amazon API Gateway. The developer needs to trace requests as they travel through different services to identify performance bottlenecks. Which AWS service should the developer integrate?

An independent software vendor (ISV) is building a serverless application that processes incoming HTTP requests. The incoming requests must be validated against an OpenAPI schema before being passed to the Lambda function. Which AWS service should the ISV use to perform this validation?

A developer is building a serverless web application using AWS Lambda and Amazon DynamoDB. The application needs to perform complex aggregations on data stored in DynamoDB. Which AWS service should the developer use to perform these aggregations efficiently without reading all the data into Lambda?

A developer is building a serverless API using Amazon API Gateway and AWS Lambda. The API accepts JSON payloads in the request body. The developer wants to ensure that incoming requests have a valid structure before being passed to the Lambda function to reduce unnecessary invocations. Which API Gateway feature should the developer use?

A developer is building a RESTful API using Amazon API Gateway. The API experiences high traffic spikes, and many requests are for the same data (e.g., a product catalog). The developer wants to reduce the load on the backend Lambda functions and improve response times for repeated requests. Which feature should the developer enable?

A developer is building an application that needs to store session state data for a web application running on multiple EC2 instances behind an ALB. The data is ephemeral and should not persist if an instance is terminated. Which storage option should the developer use?

A developer is building a REST API using Amazon API Gateway and wants to transform the request data before sending it to the backend Lambda function. The transformation includes mapping query string parameters to a JSON body. Which API Gateway feature should be used?

A developer is building a RESTful API using Amazon API Gateway and Lambda. The API should support CORS for a specific origin (https://example.com) and allow only GET and POST methods. Which configuration in the OPTIONS method response will satisfy these requirements?

A company wants to build a RESTful API that handles file uploads. The API needs to support multipart/form-data content type. The developer is using Amazon API Gateway and AWS Lambda. Which approach should the developer use to handle file uploads efficiently?

A developer is building a web application that requires user authentication. The application will run on Amazon EC2 instances behind an Application Load Balancer. The developer wants to offload authentication to a managed service that supports social login providers. Which AWS service should the developer use?

A developer is using Amazon API Gateway with a Lambda authorizer to control access to an API. The authorizer function needs to decode a JWT token from the request header and return an IAM policy. Which type of Lambda authorizer should be used?

A developer is building a serverless application that needs to process messages from an Amazon SQS queue and store the results in an Amazon DynamoDB table. Which AWS service should the developer use to orchestrate the processing logic without managing servers?

A developer is building a REST API using Amazon API Gateway and wants to validate the incoming request body against a JSON schema before passing the request to the backend Lambda function. Which API Gateway feature should the developer use?

A developer is building a serverless REST API using Amazon API Gateway and AWS Lambda. The API will be consumed by a web application hosted on a different domain. The developer needs to enable Cross-Origin Resource Sharing (CORS) for all HTTP methods. What is the most efficient way to achieve this?

A developer has an Amazon S3 bucket containing private user documents. The application must generate a time-limited URL for users to download their own documents without requiring the users to have AWS credentials. Which solution should the developer use?

A developer is building a microservices application that processes event messages from multiple sources. The application requires at-least-once delivery, but message ordering is not important. Which Amazon SQS queue type should the developer use?

A developer is building an AWS Lambda function that needs to retrieve a database password securely. The password is stored in AWS Secrets Manager and is rotated every 30 days. The function must minimize the number of API calls to Secrets Manager. Which approach should the developer use?

A developer configures an AWS Lambda function to process image files uploaded to an S3 bucket. The bucket receives a mix of .jpg, .png, and .pdf files. The developer wants to invoke the Lambda function only for image files to reduce costs. Which configuration should the developer use?

A developer is designing a REST API using Amazon API Gateway that experiences high traffic with many repeated requests for the same data. The developer wants to reduce backend load and improve response times. Which feature should the developer enable on the API Gateway method?

A developer is building a serverless REST API using Amazon API Gateway and AWS Lambda. The API should return JSON responses to client requests. The developer is using the Lambda proxy integration. What is the simplest way to return a JSON response from the Lambda function?

A developer is building a serverless application using AWS Lambda and Amazon DynamoDB. The application needs to store and retrieve session data. The session data has a TTL of 30 minutes. Which DynamoDB feature should the developer use to automatically delete expired items?

A developer is creating a new DynamoDB table to store order data. The orders have a unique order ID and are retrieved by order ID. Occasionally, the developer needs to query orders by customer ID. Which design approach would minimize costs and provide the fastest queries?

A developer is writing an AWS Lambda function that processes files uploaded to an S3 bucket. The function should only be triggered when a new object is created in a specific subfolder (e.g., /uploads/). Which S3 event notification configuration should the developer use?

A developer is building a serverless application that uses Amazon DynamoDB. The application needs to retrieve an item by its primary key frequently. Which DynamoDB API call should the developer use to achieve the lowest latency?

A developer is storing application configuration data in DynamoDB. The data is frequently accessed by partition key, and items are small (less than 1KB). The read traffic is consistent and predictable. Which read capacity mode is most cost-effective for this workload?

A developer is building a RESTful API using AWS Lambda and Amazon API Gateway. The API needs to support HTTP methods GET, POST, and DELETE. The developer wants to minimize code and operational overhead. Which API Gateway integration type should the developer use?

A developer is using AWS AppSync to build a GraphQL API. The API needs to allow clients to receive real-time updates when data changes in a DynamoDB table. Which AppSync feature should the developer use?

A developer wants to store session state data for a web application running on multiple EC2 instances behind an Application Load Balancer. The data is ephemeral and should not persist if an instance is terminated. Which storage option should the developer use?

A developer is creating an AWS Lambda function that needs to access files from an Amazon EFS file system. The Lambda function must be configured to access the VPC. Which of the following is required to allow the Lambda function to mount the EFS file system?

A developer is building a serverless application using AWS Lambda that needs to connect to an Amazon RDS MySQL database. The function will be deployed in a VPC. Which resource should the developer use to ensure secure and efficient database connections?

A developer is creating an API with Amazon API Gateway that needs to accept binary data (e.g., images) and store them directly in an S3 bucket. The developer wants to minimize backend complexity. Which integration type should be used?

A developer is building a REST API using Amazon API Gateway and AWS Lambda. The API needs to support a custom domain name and an SSL/TLS certificate. Which AWS service should the developer use to manage the SSL/TLS certificate?

A developer is building a microservice that needs to invoke another AWS Lambda function and wait for the result to continue processing. Which Lambda invocation type must the developer use to achieve synchronous invocation?

A developer is writing a Lambda function that processes images uploaded to an S3 bucket. The function needs to extract metadata from the image. Which S3 feature can be used to automatically trigger the Lambda function?

A developer is building a serverless application using AWS Lambda. The function needs to access an S3 bucket to read a configuration file. What is the best way to provide the Lambda function with the bucket name?

A developer is creating an AWS Lambda function to process events from an Amazon SQS queue. The function must process each message exactly once and in order. Which SQS queue type should the developer use?

A Lambda function processes messages from an SQS standard queue and writes results to DynamoDB. Duplicate writes occasionally occur after retries. Which two changes best make the processing idempotent?

An API Gateway REST API invokes Lambda synchronously. Clients receive 502 responses after a deployment, but Lambda logs show a successful business operation. What is the most likely issue?

A Step Functions workflow calls three independent Lambda functions and should continue only after all results are available. Which state pattern should be used?

A developer needs an S3 upload workflow where clients upload large files directly to S3 without exposing AWS credentials through the browser. What should the backend generate?

A DynamoDB table uses partition key customerId. One enterprise customer generates most traffic and is throttled while the table has unused capacity elsewhere. What design change best addresses the hot partition?

A Lambda function receives events from EventBridge. The developer wants failed invocations to be retried and then stored for later analysis if retries are exhausted. Which configuration should be used?

A service publishes order events to SNS. Several consumers need different filtered subsets of events without changing publisher code. What should the developer configure?

A Lambda function must retrieve feature flags at runtime with low latency and controlled rollout. Which AWS service is most appropriate?

A developer uses the AWS SDK to list thousands of DynamoDB items from a query. Only the first page is processed. What should be implemented?

A Kinesis consumer Lambda shows increasing IteratorAge. Which two changes may improve throughput when processing is CPU-bound?

A developer wants exactly-once processing semantics for commands submitted to a queue where duplicate command IDs must be rejected within five minutes. Which SQS feature is most directly relevant?

A Lambda function must share reusable validation code across several functions without packaging the same library into every deployment artifact. What should be used?

An application uses DynamoDB Streams to trigger downstream processing. The processor must receive both old and new item images after updates. Which stream view type should be configured?

A REST API requires request validation before invoking Lambda to reduce unnecessary function executions for malformed payloads. Where should validation be configured?

A developer wants a Lambda function to process SQS messages in batches but avoid losing the whole batch when only one record fails. Which feature should be enabled?

A service needs loosely coupled asynchronous communication where one producer sends events to many different AWS service targets using rules. Which service fits best?

A Lambda function connects to an RDS database and causes too many database connections during traffic spikes. Which service should be introduced?

A developer must locally test a SAM-based Lambda function with an API event before deployment. Which tool command family is designed for this?

An application stores session data in DynamoDB and must expire sessions automatically after a timestamp. Which feature should be used?

A Lambda function needs temporary scratch space larger than the default while processing images. Which setting should be adjusted?

A Lambda function writes order records to DynamoDB after receiving API Gateway requests. Which two practices improve reliability during client retries?

A developer is implementing S3 multipart upload for large files. Which two actions are required to complete the upload?

An event-driven application uses EventBridge rules to route partner events. Which two design choices improve maintainability?

A DynamoDB query must support lookup by email address as well as by user ID. Which two changes may be required?

A Lambda function processes a batch of SQS messages. Which two configurations reduce duplicate or failed-message impact?