DVA-C02 Development with AWS Services Practice Test 13 — 15 Questions

Question 1

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?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Enable API Gateway caching. API Gateway caching stores responses from backend endpoints for a configurable Time-to-Live (TTL). When a request for the same data arrives, API Gateway serves the cached response directly without invoking the backend, reducing load and improving latency. This is the most straightforward and managed solution for repeated requests at the API layer.

Answer

Implement caching in the Lambda function using a local cache

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Use an Amazon ElastiCache Redis cluster and modify the Lambda function to check the cache first

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Place an Amazon CloudFront distribution in front of API Gateway

Question 2

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?

Accepted Answer

Return a dictionary containing 'statusCode', 'headers', and 'body' with 'body' as a JSON string.. With Lambda proxy integration, API Gateway passes the entire request to the Lambda function and expects the function to return a specific response format. The simplest way to return a JSON response is to return a dictionary (or object) containing 'statusCode', 'headers', and 'body', where 'body' is a JSON string. This format is required by API Gateway to correctly interpret the Lambda output and forward it to the client.

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Return a string from the Lambda handler.

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Use API Gateway integration response and mapping templates to transform the Lambda output.

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Return a JSON object from Lambda and set a Content-Type header in the API Gateway method response.

Question 3

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?

Accepted Answer

Use the order ID as the partition key and create a global secondary index on customer ID. Using the order ID as the partition key ensures the most efficient primary key access for the primary query pattern (retrieving by order ID). Creating a Global Secondary Index (GSI) on customer ID allows efficient querying by customer ID without scanning the base table, and GSIs have separate read/write capacity from the base table, so you only pay for the index when it is used. This design minimizes costs by avoiding unnecessary scans and provides the fastest queries for both access patterns.

Answer

Use the customer ID as the partition key and order ID as the sort key

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Use the order ID as the partition key and scan the table for customer ID queries

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Use the customer ID as the partition key and create a local secondary index on order ID

Question 4

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?

Accepted Answer

Configure the event notification with a prefix filter set to 'uploads/' and event type 's3:ObjectCreated:*'.. S3 event notifications support prefix filtering, which allows you to specify a key prefix (e.g., 'uploads/') so that only object creation events in that subfolder trigger the Lambda function. By setting the event type to 's3:ObjectCreated:*', the function responds to all object creation operations (PUT, POST, Copy, etc.) within the filtered path, meeting the requirement precisely without unnecessary invocations.

Answer

Configure a single event notification for all objects and filter on the prefix inside the Lambda function.

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Configure the event notification using object tags to filter events.

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Use AWS CloudTrail to detect S3 PutObject events and trigger Lambda.

Question 5

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?

Accepted Answer

GetItem. The GetItem API call is the most efficient way to retrieve a single item by its primary key in DynamoDB, as it directly accesses the item using the hash key (and optionally the sort key) with consistent, single-digit millisecond latency. Unlike Scan or Query, GetItem does not need to evaluate any conditions or filter through other items, making it the lowest-latency option for this specific use case.

Answer

Scan

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Query

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BatchGetItem

Question 6

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?

Accepted Answer

Lambda proxy integration. Lambda proxy integration is correct because API Gateway passes the entire HTTP request (method, path, headers, query string, body) directly to the Lambda function as a structured event, and the function returns a formatted response object. This eliminates the need to write mapping templates or configure method/request/response transformations, minimizing both code and operational overhead. It natively supports GET, POST, DELETE, and any other HTTP method without per-method configuration.

Answer

Lambda custom integration

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HTTP integration

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Mock integration

Question 7

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?

Accepted Answer

Subscriptions. Subscriptions in AWS AppSync are the feature designed for real-time updates. They use WebSocket connections to push data to clients automatically when a mutation modifies the underlying data source, such as a DynamoDB table. By configuring a subscription on a specific mutation, the developer enables clients to receive live changes without polling.

Answer

Resolvers

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Queries

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Mutations

Question 8

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?

Accepted Answer

The Lambda function must have the AWSLambdaVPCAccessExecutionRole managed policy attached.. The AWSLambdaVPCAccessExecutionRole managed policy provides the necessary permissions for Lambda to manage elastic network interfaces (ENIs) in a VPC, which is required for Lambda to connect to an EFS file system via mount targets. Without this policy, the Lambda function cannot create or manage the ENI needed to route traffic to the EFS mount target within the VPC.

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The Lambda function must be in the same Availability Zone as the EFS mount target.

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The Lambda function must have the AmazonElasticFileSystemClientReadWriteAccess managed policy attached.

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The Lambda function must have the efs:MountFileSystem permission in its execution role.

Question 9

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?

Accepted Answer

RDS Proxy. RDS Proxy is the correct choice because it manages a pool of database connections, allowing Lambda functions to reuse them efficiently and avoid exhausting MySQL connection limits under high concurrency. It also enforces IAM authentication and securely stores credentials in AWS Secrets Manager, eliminating the need to hardcode database passwords in the function code.

Answer

NAT Gateway

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VPC Endpoint

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AWS PrivateLink

Question 10

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?

Accepted Answer

AWS service integration with S3. AWS service integration with S3 allows API Gateway to directly proxy binary data (e.g., images) to an S3 bucket without invoking a Lambda function or other backend. This minimizes backend complexity because the API Gateway handles the request transformation and passes the payload directly to S3 via the PutObject API action, eliminating the need for custom code.

Answer

Lambda proxy integration

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HTTP integration

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Mock integration

Question 11

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?

Accepted Answer

AWS Certificate Manager (ACM). AWS Certificate Manager (ACM) is the correct service for provisioning, managing, and deploying SSL/TLS certificates for use with AWS services like API Gateway. ACM integrates directly with API Gateway to automatically renew certificates and attach them to custom domain names, ensuring secure HTTPS connections without manual intervention.

Answer

AWS Key Management Service (AWS KMS)

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AWS Identity and Access Management (IAM)

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AWS Secrets Manager

Question 12

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?

Accepted Answer

RequestResponse. The RequestResponse invocation type is the correct choice for synchronous invocation of a Lambda function, where the caller waits for the function to execute and receive a response. This is the default invocation type when using the Invoke API with InvocationType set to 'RequestResponse', and it is required for microservices that need to block until the downstream Lambda returns a result.

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Event

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DryRun

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None of the above

Question 13

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?

Accepted Answer

S3 Events. Amazon S3 Events can be configured to send a notification when an object is created (e.g., via PutObject) in an S3 bucket. This event can directly invoke an AWS Lambda function, making it the correct service to automatically trigger the function upon image upload. The developer simply needs to set up an S3 event notification with the Lambda function as the destination.

Answer

S3 Inventory

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S3 Transfer Acceleration

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S3 Batch Operations

Question 14

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?

Accepted Answer

Store the bucket name in an environment variable for the Lambda function.. AWS Lambda environment variables provide a secure, configurable, and decoupled way to pass the S3 bucket name to the function without hardcoding it in the code. This follows the principle of infrastructure as code and allows the same function code to be reused across different environments (e.g., dev, staging, prod) by simply changing the environment variable value. Environment variables are encrypted at rest by default using AWS KMS, ensuring the bucket name is not exposed in plaintext within the code repository.

Answer

Hardcode the bucket name in the Lambda function code.

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Read the bucket name from a text file stored in the same bucket.

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Use a KMS key to encrypt the bucket name and decrypt it in the function.

Question 15

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?

Accepted Answer

FIFO queue.. FIFO queue. FIFO (First-In-First-Out) queues guarantee exactly-once processing and preserve the order of messages, which is required by the use case. Standard queues offer at-least-once delivery and do not guarantee order, making them unsuitable for this requirement.

Answer

Standard queue.

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Dead-letter queue.

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Delay queue.