Development with AWS Services — AWS Certified Developer DVA-C02 practice questions

A Lambda stores connection setup outside the handler. What is the primary BENEFIT?

1. Guarantees cold start on every call
2. Enables VPC network isolation only
3. Disables CloudWatch logging output
4. Setup runs once per exec environment

Answer: D — Setup runs once per exec environment

A) Outside-handler code runs at init, not on every call. D) Correct — init runs once per exec env and reuses on warm invokes. C) Logging is unrelated. B) VPC attachment is a separate config.

Which service is BEST for orchestrating a multi-step serverless workflow with retries and branching?

1. AWS Lambda chained via SNS topics
2. Amazon EventBridge scheduled rule
3. AWS Step Functions state machine
4. Amazon SQS FIFO queue for ordering

Answer: C — AWS Step Functions state machine

C) Correct — Step Functions models Tasks, Choices, Parallel, and per-state retries. B) EventBridge routes events but is not a workflow engine. A) Chaining Lambdas via SNS is fragile and lacks state. D) SQS decouples but does not orchestrate.

Which SNS delivery protocol is BEST for pushing publishing events to a Lambda function?

1. HTTP endpoint webhook receiver
2. Email-JSON mailbox delivery
3. Lambda function direct target
4. SMS text message delivery

Answer: C — Lambda function direct target

A) HTTPS invokes a webhook, not a function directly. B) Email-JSON delivers to a mailbox. C) Correct — SNS supports Lambda subscription protocol directly. D) SMS is for text messages.

Which mechanism gives a Lambda function a stable HTTPS endpoint WITHOUT API Gateway?

1. EventBridge scheduled rule
2. SNS topic subscription push
3. SQS event source mapping
4. Lambda function URL endpoint

Answer: D — Lambda function URL endpoint

A) EventBridge is cron, not a URL. D) Correct — function URLs expose a public HTTPS endpoint directly on the function. C) SQS mapping is a queue trigger. B) SNS is push messaging.

By default, DynamoDB GetItem returns data using which consistency model?

1. Strongly consistent reads
2. Eventually consistent reads
3. Serializable reads
4. Linearizable reads

Answer: B — Eventually consistent reads

A) Available with ConsistentRead=true but costs twice as many RCUs. B) Correct — default GetItem is eventually consistent; cheapest and lowest latency. C) A relational-DB term; DynamoDB does not use it for reads. D) Not a DynamoDB read mode; sounds authoritative but is a distractor.

Which SDK feature streams paginated results without loading them all in memory?

1. A single ListObjects call full
2. While-true loop reading offsets
3. Paginator or async iterator interface
4. S3 Select over a byte range

Answer: C — Paginator or async iterator interface

A) A single call returns a truncated page. C) Correct — paginators auto-fetch the next page transparently. B) Manual offset loops must handle continuation tokens. D) S3 Select is server-side SQL, not pagination.

Which SQS attribute controls how long a message is HIDDEN after a consumer receives it?

1. VisibilityTimeout for in-flight
2. MessageRetentionPeriod for queue
3. ReceiveMessageWaitTimeSeconds
4. DelaySeconds for new messages

Answer: A — VisibilityTimeout for in-flight

B) Retention governs how long unprocessed messages remain in the queue. A) Correct — VisibilityTimeout hides an in-flight message until deleted or timed out. C) WaitTime controls long polling. D) DelaySeconds hides NEW messages before first delivery.

Which S3 feature grants time-limited credential-less GET access to a private object?

1. Public bucket ACL grant
2. Pre-signed URL with expiry
3. IAM group membership assign
4. S3 replication rule pull

Answer: B — Pre-signed URL with expiry

A) Making the bucket public defeats the goal. B) Correct — pre-signed URLs embed a signature that expires; no client AWS credentials needed. C) Group membership is for IAM users. D) Replication copies objects.

How does SNS + SQS fan-out ensure downstream isolation between multiple consumers?

1. Each consumer has its own SQS queue subscribed
2. Each consumer polls one shared queue
3. All consumers share a single Lambda
4. Consumers register long-poll to SNS

Answer: A — Each consumer has its own SQS queue subscribed

B) Sharing one queue prevents parallel consumers. A) Correct — the fan-out pattern gives each consumer its own SQS queue subscribed to the same topic. C) A single function is not fan-out. D) SNS does not accept long-poll registrations.

Which Lambda destination event is emitted when a synchronous invocation fails after retries?

1. Failure event to Destinations target
2. Success event to configured target
3. SNS email to the account owner
4. CloudTrail-only log entry emit

Answer: A — Failure event to Destinations target

B) Success destinations fire only when the function succeeds. A) Correct — the on-failure Destination target receives the failure payload after retries. C) SNS emails aren't automatic. D) CloudTrail alone doesn't capture the payload.

What is Kinesis?

Real-time data streams. Data Streams (raw), Firehose (delivery), Analytics (SQL), Video Streams.

What is SQS?

Simple Queue Service. Managed message queue. Decouples producers/consumers.

AWS CLI authentication methods?

Access keys, profiles, IAM role (EC2/ECS), SSO, web identity federation.

ElastiCache engines?

Redis (advanced features) and Memcached (simple, multi-threaded).