DVA-C02 Practice Exam 60 — 20 Questions

Question 1

A developer deployed a new Lambda function that processes messages from an SQS queue. The function runs correctly for small workloads but starts timing out after 15 seconds when traffic increases. The function has a reserved concurrency of 10 and a timeout of 30 seconds. CloudWatch logs show occasional throttling errors (429). What is the MOST likely cause?

Accepted Answer

The reserved concurrency is too low.. Option D is correct because the function is experiencing throttling due to insufficient reserved concurrency, causing requests to be delayed and eventually time out. Option A is wrong because the timeout is set to 30 seconds, but the issue is throttling, not timeout. Option B is wrong because SQS batch size does not cause throttling. Option C is wrong because Lambda scales horizontally, not vertically.

Answer

The function memory is too low.

Answer

The SQS batch size is too large.

Answer

The function timeout is too low.

Question 2

A developer is troubleshooting an AWS Lambda function that writes to an S3 bucket. The function is failing with an 'AccessDenied' error. The Lambda execution role has the following policy. What is the likely issue?

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:PutObject",
        "s3:GetObject"
      ],
      "Resource": "arn:aws:s3:::my-bucket/*"
    }
  ]
}

Accepted Answer

The bucket uses SSE-KMS encryption, and the role lacks kms:Decrypt permission.. Option A is correct because the policy only grants access to objects in the bucket, not to the bucket itself for operations like ListBucket, but for PutObject, the resource is correct. However, the error may be due to a missing permission for s3:PutObject on the bucket level if the bucket policy also requires it. Actually, the most common issue for PutObject is the resource ARN, which is correct. But if the bucket is encrypted, you need kms:Decrypt permissions. Option A points to missing KMS permissions, which is plausible. Option B is wrong because the resource is correct. Option C is wrong because S3 does not require s3:ListBucket for PutObject. Option D is wrong because the action is allowed.

Answer

The resource ARN should be 'arn:aws:s3:::my-bucket' instead of 'my-bucket/*'.

Answer

The action should be 's3:PutObject' only, not 's3:GetObject'.

Answer

The role is missing s3:ListBucket permission.

Question 3

A developer is debugging an AWS Lambda function that is invoked by an Amazon S3 event notification. The function sometimes fails with a 'ResourceNotFoundException' when trying to access a DynamoDB table. The function's execution role has the following policy:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "dynamodb:*",
      "Resource": "arn:aws:dynamodb:us-east-1:123456789012:table/MyTable"
    }
  ]
}

What are TWO possible causes for this intermittent failure?

Accepted Answer

The DynamoDB table name contains a typo in the Lambda code.. Option B is correct because if the table is in a different region, the resource ARN region would be wrong. Option D is correct because if the table name is different, the ARN would not match. Option A is wrong because the policy allows all DynamoDB actions. Option C is wrong because the function has the policy. Option E is wrong because VPC endpoints do not affect IAM permissions.

Answer

The Lambda function's execution role is not attached to the function.

Answer

The Lambda function is inside a VPC without a DynamoDB VPC endpoint.

Answer

The IAM policy does not include the 'dynamodb:GetItem' action specifically.

Question 4

A developer is creating an ECS task definition using the JSON shown in the exhibit. The task fails to run with an error about insufficient memory. What is the issue?

Accepted Answer

The task memory and cpu values are specified as strings instead of integers.. Option A is correct because the container memory (256) plus task memory (512) must be consistent; the task memory is 512 but the container memory is 256, which is okay, but the error indicates the container memory is higher than task memory? Actually, the task memory is 512, container memory 256, so it's fine. However, the exhibit shows task memory as a string '512' and CPU as '256'; they should be integers. Option A is the most likely: the task memory is set to 512 but the container memory is 256, which is less, so that's not an issue. Wait, the error is about insufficient memory. Perhaps the container memory should be equal to task memory? Actually, the error might be because the task memory is not enough for the container? The container memory is 256, task memory 512, so that's fine. Let me reconsider. The exhibit shows 'memory': '512' (string) and 'cpu': '256' (string). In ECS task definition, memory and cpu must be integers, not strings. That could cause the task to fail. Option B is correct: the values are strings. Option A is wrong because container memory is less than task memory. Option C is wrong because container port mapping is valid. Option D is wrong because network mode is not specified, but default is bridge which is fine.

Answer

The container port is not mapped to a host port.

Answer

The task definition does not specify a network mode.

Answer

The container memory is less than the task memory.

Question 5

A developer is investigating why an Amazon API Gateway REST API is returning 504 errors during peak traffic. The API integrates with a Lambda function. Which TWO factors are MOST likely causing the 504 errors? (Choose TWO.)

Accepted Answer

The Lambda function is hitting its reserved concurrency limit and being throttled.. Option A and Option B are correct. Option A: If the Lambda function's timeout is less than the API Gateway integration timeout (29 seconds), the function may timeout before the API Gateway, causing a 504. Option B: If the Lambda function is throttled, API Gateway receives a 429 from Lambda and returns a 504. Option C (API Gateway throttling) would cause 429, not 504. Option D (cache) would not cause 504. Option E (WAF) would cause 403.

Answer

The API Gateway cache is full and cannot store responses.

Answer

The AWS WAF is blocking the request.

Answer

The API Gateway account-level throttling limits are exceeded.

Question 6

A developer notices that an Amazon RDS for MySQL DB instance's CPU utilization is consistently above 90% during peak hours. The application uses read-heavy workloads. Which action would MOST effectively reduce CPU load without major architectural changes?

Accepted Answer

Create a Multi-AZ deployment and use the standby for read queries.. Option B is correct because adding a read replica offloads read queries from the primary instance, reducing CPU usage for read-heavy workloads. Option A (increasing instance size) might help but is less cost-effective and does not address read vs write separation. Option C (ElastiCache) adds caching but requires application changes. Option D (Aurora) involves migration effort.

Answer

Implement an in-memory cache layer with Amazon ElastiCache.

Answer

Migrate the database to Amazon Aurora with auto-scaling.

Answer

Increase the DB instance size to a larger instance type.

Question 7

A developer is optimizing an application that uses Amazon DynamoDB. The application reads items by primary key and also performs queries on a Global Secondary Index (GSI). The developer notices that some queries on the GSI are slow. Which TWO actions would improve the performance of GSI queries? (Choose TWO.)

Accepted Answer

Use a more distributed GSI partition key to avoid hot partitions.. Option A and Option B are correct. Option A: If the GSI is sparse (not all items have the GSI key attribute), the index may not have enough data to distribute reads; adding a filter condition can help. Actually, ensuring that the GSI key attribute exists on all items that need to be queried can improve performance. Option B: Overloading the GSI partition key can cause hot partitions; using a more distributed key pattern helps. Option C (adjust write capacity) does not directly help read performance on GSI. Option D (use strong consistency) would actually increase latency. Option E (increase read capacity) could help if the issue is throttling, but the question asks for two actions. Let me reconsider: The correct options should be: B (use a more distributed GSI partition key) and E (increase read capacity on the index) if the issue is throttling. However, increasing read capacity on the index is not directly possible; you increase read capacity on the table, which is shared with GSIs. Actually, GSIs use the same read capacity units as the table. So option E is not accurate. Option C says 'Increase the write capacity of the table' which would not help read performance. Option D 'Use strongly consistent reads' would be slower. So the best two are: B (redistribute keys) and A (ensure GSI key attribute exists on queried items) to avoid sparse index. Let me adjust the correct answers.

Answer

Increase the read capacity of the GSI.

Answer

Use strongly consistent reads on the GSI.

Answer

Increase the write capacity of the DynamoDB table.

Question 8

A Lambda function is timing out after 3 seconds when processing an S3 event. The function reads a file from S3 and writes to DynamoDB. The timeout is set to 5 seconds. What is the MOST likely cause of the timeout?

Accepted Answer

The function is attached to a VPC without a NAT gateway, causing network timeouts when accessing S3 and DynamoDB.. Option C is correct because the default Lambda timeout is 3 seconds, and the function's configured timeout (5 seconds) is higher, so it should not timeout at 3 seconds unless the function itself is hanging. However, the stem says 'timing out after 3 seconds' which suggests the function execution is being terminated at 3 seconds. The most common cause is that the function's configured timeout is actually 3 seconds (not 5 as stated). But the stem says 'the timeout is set to 5 seconds', so if it times out at 3, it could be due to a VPC configuration causing network delays. Actually, the most likely cause is that the function is in a VPC without a proper internet gateway or NAT gateway, causing network calls to S3 and DynamoDB to hang. Option C addresses that. Option A (insufficient memory) would cause slower execution but not a hard timeout at exactly 3 seconds. Option B (concurrency limit) would cause throttling, not timeout. Option D (DynamoDB throttling) would cause retries and slower performance but not a hard timeout at 3 seconds.

Answer

DynamoDB write capacity is insufficient, causing write requests to be throttled.

Answer

The function's memory allocation is too low, causing CPU throttling.

Answer

The function is hitting the reserved concurrency limit and being throttled.

Question 9

A developer is deploying a web application on Amazon ECS with Fargate. The application needs to store session state. Which THREE options are suitable for storing session state in a distributed environment? (Choose THREE.)

Accepted Answer

Amazon RDS for MySQL. Option A, option C, and option D are correct. Option A: ElastiCache for Redis is commonly used for session storage. Option C: DynamoDB is a good choice for session state due to low latency and scalability. Option D: RDS for MySQL can be used but is less common due to relational overhead; however, it is still a valid option. Option B (local ephemeral storage) is not suitable because it is not shared across tasks. Option E (S3) is not designed for frequent read/write session data; it is object storage with higher latency.

Answer

Amazon S3

Answer

Local ephemeral storage on the Fargate task

Question 10

A company is using Amazon DynamoDB with on-demand capacity. A developer notices that write requests are being throttled during peak hours. What is the MOST effective way to resolve this issue?

Accepted Answer

Review the partition key design and consider adding a suffix to distribute writes.. Option D is correct because on-demand capacity can still throttle if you exceed the previous peak traffic by a large margin; the table can be split into multiple partitions to distribute write load. Option A is wrong because on-demand already auto-scales. Option B is wrong because increasing read capacity does not help writes. Option C is wrong because there are no WCU limits in on-demand mode.

Answer

Switch to provisioned capacity mode with auto-scaling.

Answer

Increase the write capacity units.

Answer

Increase the read capacity units.

Question 11

A developer is troubleshooting an application that uses Amazon SQS. Messages are being sent to a dead-letter queue (DLQ) after the maximum receive count is exceeded. The consumer processes messages but sometimes fails. The developer wants to ensure that messages are retried immediately after a failure, without waiting for the visibility timeout. Which solution should the developer implement?

Accepted Answer

After a failure, call ChangeMessageVisibility with a timeout of 0 to make the message immediately available for reprocessing.. Option D is correct because calling ChangeMessageVisibility with a timeout of 0 makes the message immediately visible to other consumers for retry. Option A (delete and re-send) would create a new message with a new message ID, losing the original message attributes. Option B (increase visibility timeout) would delay retry. Option C (delay queue) would add a delay before the message becomes available, which is opposite of what is needed.

Answer

Configure a delay queue so that messages are not immediately visible after failure.

Answer

Delete the message from the queue and re-send it after processing failure.

Answer

Increase the visibility timeout to allow more time for processing.

Question 12

A developer is troubleshooting an AWS CloudFormation stack creation failure. The stack creation failed with the error: 'Resource creation cancelled'. What does this error typically indicate?

Accepted Answer

Another resource in the stack failed, causing a rollback.. Option B is correct because 'Resource creation cancelled' means a different resource in the stack failed, causing rollback. Option A is wrong because insufficient IAM permissions would give an access denied error. Option C is wrong because the error is not about template validation. Option D is wrong because the error is not about resource limit.

Answer

The IAM user does not have permission to create the resource.

Answer

The template has a syntax error.

Answer

The resource type is not supported by CloudFormation.

Question 13

A developer is using AWS CodeBuild to build a Java application. The build succeeds locally but fails on CodeBuild with a 'Cannot find symbol' error for a class that is in a dependency JAR. What is the MOST likely cause?

Accepted Answer

The dependency cache is not enabled in CodeBuild, so dependencies are not available.. Option C is correct because CodeBuild by default does not include cached dependencies; each build downloads dependencies from scratch unless a cache is configured. The local build works because Maven/Gradle caches dependencies locally. Option A (buildspec syntax) would cause a different error. Option B (build timeout) would cause a timeout, not a compilation error. Option D (insufficient compute) would cause performance issues but not a missing symbol.

Answer

The build is timing out before dependencies are fully downloaded.

Answer

The CodeBuild compute type does not have enough memory to compile the project.

Answer

The buildspec file has incorrect syntax causing the build to skip dependency resolution.

Question 14

A developer is optimizing an AWS Lambda function that processes streaming data from Amazon Kinesis. The function is CPU-bound. Which TWO actions should the developer take to improve performance?

Accepted Answer

Rewrite the function in a compiled language like Go.. Option A is correct because increasing memory also increases CPU allocation. Option C is correct because using a language with better CPU performance (e.g., Go) can improve speed. Option B is wrong because increasing reserved concurrency does not affect individual function performance. Option D is wrong because Lambda does not support GPU. Option E is wrong because Kinesis batch size does not affect CPU-bound processing.

Answer

Increase the function's reserved concurrency.

Answer

Increase the Kinesis stream's shard count.

Answer

Enable GPU acceleration for the function.

Question 15

A developer is using AWS CloudFormation to deploy a stack. The stack creation fails with the error 'API: iam:CreateRole User: arn:aws:iam::123456789012:user/DevUser is not authorized to perform: iam:CreateRole'. The developer is using an IAM user with AdministratorAccess policy attached. What is the MOST likely cause of this error?

Accepted Answer

The CloudFormation stack is using a service role that does not have iam:CreateRole permission.. Option D is correct because CloudFormation uses a service role to create resources if a service role is specified. If the service role does not have the necessary permissions, the stack creation will fail even if the user has full permissions. Option A (region issue) is not relevant. Option B (resource limit) would give a limit exceeded error. Option C (policy version) would not cause this specific error.

Answer

The account has reached the IAM role limit.

Answer

The CloudFormation stack is being created in a region where IAM is not supported.

Answer

The AdministratorAccess policy has been modified to remove IAM permissions.

Question 16

A developer uses the CloudFormation template in the exhibit to create an S3 bucket. The stack creation fails with the error 'Bucket already exists'. What is the MOST likely reason?

Accepted Answer

The bucket name is already taken by another AWS account.. Option B is correct because S3 bucket names must be globally unique. If the bucket name 'my-unique-bucket-name' already exists in another AWS account, the creation will fail. Option A (region) is not true; bucket names are global. Option C (permissions) would cause a different error. Option D (template format) is valid JSON.

Answer

The CloudFormation template has invalid JSON syntax.

Answer

The IAM user does not have permission to create S3 buckets.

Answer

The bucket name is not available in the specified region.

Question 17

A company is using Amazon S3 to store large objects. Users report that uploads are slow. Which THREE actions should the developer take to optimize upload performance?

Accepted Answer

Use multipart upload for objects over 100 MB.. Option A is correct because multipart upload improves performance for large objects. Option B is correct because using S3 Transfer Acceleration reduces latency. Option C is correct because using S3 prefixes increases request rate performance. Option D is wrong because S3 Select is for retrieving subsets of data, not uploads. Option E is wrong because Glacier is for archival, not for active uploads.

Answer

Use S3 Select to upload only specific parts of the object.

Answer

Transition objects to S3 Glacier after upload.

Question 18

A developer deployed a new version of a Lambda function using an alias that points to the new version. However, the function continues to invoke the old version. What is the MOST likely cause?

Accepted Answer

The alias was not updated to point to the new version after deployment.. Option B is correct because if the version number in the alias is not updated, the alias still points to the old version. Option A (concurrency) does not affect which version is invoked. Option C (different function name) would cause a different error. Option D (IAM permissions) would cause access denied errors, not invocation of old code.

Answer

The IAM execution role for the Lambda function does not have permission to invoke the new version.

Answer

The Lambda function's reserved concurrency is set to 0, preventing new invocations.

Answer

The function name in the invocation request is different from the deployed function.

Question 19

A developer is troubleshooting a Lambda function that intermittently times out. The function makes HTTP requests to an external API. The function's CloudWatch logs show 'Task timed out after 3.01 seconds'. What is the MOST likely cause?

Accepted Answer

The Lambda function timeout is set to 3 seconds, but the HTTP request takes longer.. Option C is correct because the Lambda function timeout is set to 3 seconds by default, causing the timeout error. Option A is wrong because VPC configuration does not cause timeout logs about 'Task timed out' - that message specifically refers to the function timeout. Option B is wrong because the function has no reserved concurrency issue. Option D is wrong because the logs indicate the function started execution.

Answer

The Lambda function has insufficient reserved concurrency causing throttling.

Answer

The Lambda function is not configured with a VPC and cannot reach the external API.

Answer

The Lambda function is not starting execution due to a missing IAM role.

Question 20

A developer runs the AWS CLI command shown in the exhibit. The output includes 'FunctionError': 'Unhandled'. What does this indicate?

Accepted Answer

The function threw an unhandled exception.. Option C is correct because 'Unhandled' means the function returned an error that was not caught by the code. Option A is wrong because StatusCode 200 indicates successful invocation, not failure to invoke. Option B is wrong because a handled error would show 'Handled'. Option D is wrong because a timeout would be a different error.

Answer

The function threw an error that was caught by the code.

Answer

The function timed out.

Answer

The function was not invoked successfully.