DVA-C02 Practice Test 8 — 10 Questions

Question 1

A company uses AWS CloudFormation to deploy infrastructure. They have a stack that creates an Amazon RDS DB instance. They want to update the DB instance class without downtime. Which update policy should they use?

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

Accepted Answer

UseLatestRestorableTime. None of the listed options is correct. AWS CloudFormation does not have a built-in update policy that avoids downtime when changing the DB instance class of an RDS instance. To modify the instance class with minimal downtime, you can use a custom approach such as creating a read replica, promoting it, and updating DNS, or modifying the DB instance directly (which typically involves brief downtime). The options presented are either invalid or unrelated: UseLatestRestorableTime is a property for restoring from a snapshot or creating read replicas, not an update policy; AutoScalingRollingUpdate is for Auto Scaling groups; UpdateReplacePolicy controls replacement behavior; CreationPolicy controls creation signals.

Answer

AutoScalingRollingUpdate

Answer

UpdateReplacePolicy

Answer

CreationPolicy

Question 2

A developer is managing an application running on Amazon EC2 instances behind an Application Load Balancer. Users report that the application becomes unresponsive after several hours, and restarting the instance temporarily fixes the issue. The developer suspects a memory leak but cannot add custom instrumentation. Which AWS service can collect memory utilization metrics and help identify the memory leak with minimal configuration?

Accepted Answer

Install the CloudWatch agent on the EC2 instances to collect memory metrics and emit them to CloudWatch.. The CloudWatch agent can collect custom metrics, including memory utilization, from EC2 instances and publish them to Amazon CloudWatch. This allows the developer to monitor memory usage over time and identify a memory leak without modifying the application code. The default EC2 metrics do not include memory utilization, so the CloudWatch agent is the minimal-configuration solution for this requirement.

Answer

Use Amazon CloudWatch Logs agent to capture application logs.

Answer

Use the EC2 instance metadata service to query memory usage.

Answer

Use AWS X-Ray to trace memory allocation.

Question 3

A company runs a containerized application on Amazon ECS Fargate. The application writes logs to stdout. The operations team wants to centralize log monitoring and set up alarms for error patterns. What should a developer do to meet these requirements with minimal operational overhead?

Accepted Answer

Configure the ECS task definition to use the awslogs log driver and set the log group.. The awslogs log driver is the native, zero-configuration way to send container stdout/stderr to Amazon CloudWatch Logs from ECS Fargate. By specifying the awslogs log driver and a log group in the task definition, logs are automatically forwarded without any additional agents, code changes, or infrastructure, meeting the requirement for minimal operational overhead.

Answer

Use Amazon Kinesis Data Firehose to stream logs to Amazon S3 and then to CloudWatch Logs.

Answer

Modify the application code to use the AWS SDK for CloudWatch Logs to put log events.

Answer

Install the CloudWatch agent in the container and configure it to send logs.

Question 4

A developer needs to grant a Lambda function permission to write logs to CloudWatch Logs. Which IAM entity should be used?

Accepted Answer

Create an IAM execution role with the necessary permissions and associate it with the function.. Lambda functions require an IAM execution role to obtain temporary credentials for accessing other AWS services. This role must include a trust policy allowing Lambda to assume it and a permissions policy granting the specific actions (e.g., logs:CreateLogGroup, logs:CreateLogStream, logs:PutLogEvents) on CloudWatch Logs. Associating this role with the function is the standard and secure way to grant permissions.

Answer

Attach an inline policy to the Lambda function.

Answer

Use a service control policy (SCP) to allow logging.

Answer

Add a resource-based policy to the Lambda function.

Question 5

A developer is building a real-time chat application using WebSockets via API Gateway. The backend uses AWS Lambda functions to handle connect, disconnect, and message events. The application needs to broadcast messages to all connected clients. What is the most scalable and cost-effective way to maintain the list of connection IDs and broadcast messages?

Accepted Answer

Store connection IDs in a DynamoDB table. Use a Lambda function to query all connection IDs and send messages using the API Gateway Management API.. DynamoDB provides a scalable and cost-effective solution for storing connection IDs because it is a NoSQL database designed for high availability and low latency. The Lambda function can query the entire table to retrieve all connection IDs and then use the API Gateway Management API (via `postToConnection`) to send messages to each client. This approach scales horizontally because multiple Lambda instances can access the same DynamoDB table. Option A is wrong because SQS FIFO queues are not suitable for broadcasting all messages to all connections; they are designed for point-to-point messaging and would require polling, adding latency and cost. Option C is wrong because an in-memory list in a single Lambda instance does not persist across cold starts and cannot be shared across multiple concurrent Lambda instances, leading to data loss and incorrect broadcasts. Option D is wrong because ElastiCache Redis adds operational complexity and cost, and using its Pub/Sub feature would require additional infrastructure; DynamoDB is simpler and more aligned with serverless best practices.

Answer

Use an SQS FIFO queue to store connection IDs and have a Lambda function poll the queue to broadcast.

Answer

Maintain an in-memory list of connection IDs in a global variable of a single Lambda function.

Answer

Use Amazon ElastiCache Redis to store connection IDs and use Redis Pub/Sub for broadcasting.

Question 6

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?

Accepted Answer

Pagination using LastEvaluatedKey until no further key is returned. The DynamoDB Query API returns paginated results, with a maximum of 1 MB of data per page. The `LastEvaluatedKey` in the response indicates that more items exist. To retrieve all items, the application must check for `LastEvaluatedKey` and, if present, issue a subsequent Query request with the `ExclusiveStartKey` parameter set to that value, repeating until `LastEvaluatedKey` is no longer returned. This is the standard pagination pattern for DynamoDB.

Answer

A larger Lambda memory setting only

Answer

A global secondary index with the same key

Answer

Strongly consistent reads on every request

Question 7

A developer is building an application that needs to send email notifications to users. Which AWS service is designed for sending transactional emails?

Accepted Answer

Amazon Simple Email Service (SES). Amazon Simple Email Service (SES) is specifically designed for sending transactional emails, such as order confirmations, password resets, and marketing communications. It provides a reliable, scalable SMTP interface or API to send high-deliverability emails, with features like dedicated IP addresses and feedback loops. This makes it the correct choice for an application that needs to send email notifications directly to users.

Answer

AWS Lambda

Answer

Amazon Simple Notification Service (SNS)

Answer

Amazon Simple Queue Service (SQS)

Question 8

A company runs a critical web application on Amazon EC2 instances behind an Application Load Balancer. The application needs to authenticate users via an external OpenID Connect (OIDC) identity provider. The company wants to offload authentication to the load balancer and use IAM roles to access AWS resources. Which solution should the developer implement?

Accepted Answer

Configure the ALB to use the OIDC identity provider for user authentication. Use the identity token to assume an IAM role via web identity federation.. The Application Load Balancer (ALB) can directly authenticate users against an external OpenID Connect (OIDC) identity provider using its native OIDC authentication action. After successful authentication, the ALB passes the ID token to the backend application, which can then use the AWS Security Token Service (STS) AssumeRoleWithWebIdentity API to exchange the token for temporary AWS credentials, allowing the application to access AWS resources via an IAM role without managing long-term keys.

Answer

Configure the ALB target group to authenticate using the OIDC identity provider.

Answer

Use AWS Lambda@Edge to authenticate users at the edge.

Answer

Use Amazon Cognito user pools as the OIDC provider and integrate with ALB.

Question 9

A developer needs to store application configuration data that can be read by multiple EC2 instances. The data is less than 1 KB and changes frequently. Which AWS service is BEST suited for this?

Accepted Answer

AWS AppConfig. AWS AppConfig is the best choice because it is designed for dynamic, frequent configuration changes that need to be deployed to multiple EC2 instances without redeploying code or restarting applications. It supports hosted configuration data (up to 1 MB) and provides controlled rollouts, validation, and monitoring, making it ideal for sub-1 KB data that changes frequently.

Answer

Amazon S3

Answer

AWS Systems Manager Parameter Store

Answer

Amazon DynamoDB

Question 10

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.

Answer

Event

Answer

DryRun

Answer

None of the above