DEA-C01 Data Operations and Support Practice Question

A data engineer is managing an Amazon Kinesis Data Firehose delivery stream that writes to an Amazon S3 bucket. The engineer notices that some records are being delivered to the S3 bucket with a prefix of 'errors/' instead of the intended 'data/' prefix. The Firehose stream is configured with an AWS Lambda function for data transformation, and the S3 bucket has a lifecycle policy that transitions objects to Glacier after 30 days. Which TWO actions should the engineer take to ensure that only successfully transformed records are delivered to the 'data/' prefix and that failed records are handled appropriately? (Choose two.)

⚠ Common exam trap

The trap here is assuming that Firehose can dynamically route records based on status, when in fact the error prefix is a static configuration and the Lambda result status determines delivery.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Specify an error prefix in the Firehose stream's S3 destination configuration so that failed records are delivered to a separate prefix.

To ensure only successful records go to the 'data/' prefix, the Lambda function must return a 'result' of 'Ok' for successful transformations and 'Dropped' or 'ProcessingFailed' for failures. Additionally, configuring an error prefix in the Firehose S3 destination directs failed records to a separate 'errors/' prefix. Together, these actions segregate successful and failed records correctly.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
Specify an error prefix in the Firehose stream's S3 destination configuration so that failed records are delivered to a separate prefix.
Why this is correct
The S3 destination configuration for Kinesis Data Firehose includes an optional error prefix. When a record fails transformation (Lambda returns 'ProcessingFailed') or delivery, Firehose writes that record to the specified error prefix instead of the main prefix. By setting the error prefix to 'errors/', failed records are segregated, and only successfully transformed records (with 'Ok' status) are delivered to the 'data/' prefix. This is the correct way to handle failed records.
✗
Enable the 'S3 backup' setting in the Firehose stream to back up all incoming records to a separate S3 bucket before transformation.
Why it's wrong here
The S3 backup setting creates a backup of all records before transformation, but it does not control which records are delivered to the 'data/' prefix after transformation. The backup is stored in a separate bucket and is used for troubleshooting or reprocessing. It does not affect the routing of failed records to the 'errors/' prefix. Enabling backup would not solve the problem of failed records appearing in the main prefix.
✗
Increase the Firehose stream's buffer size and buffer interval to reduce the number of failed records.
Why it's wrong here
Buffer size and buffer interval control how long Firehose waits before delivering data to S3, affecting latency and file size. They do not influence whether a record passes transformation. Failed records occur because the Lambda function returns a failure status or throws an error, not because of buffering settings. Adjusting buffers would not separate failed records from successful ones and could increase latency unnecessarily.
✓
Configure the Lambda function to return the transformed record with a 'result' status of 'Ok' for successful records and 'Dropped' or 'ProcessingFailed' for failed records.
Why this is correct
In Kinesis Data Firehose, the Lambda function for transformation must return a JSON object with a 'result' field for each record. Valid values are 'Ok', 'Dropped', and 'ProcessingFailed'. If the result is 'Ok', Firehose delivers the transformed data to the destination. If 'Dropped' or 'ProcessingFailed', Firehose sends the original record to the error prefix (if configured) or drops it. Setting the correct status ensures only successful records go to the 'data/' prefix.
✗
Configure the Firehose stream's S3 destination to use a dynamic prefix based on the record's result status, such as 'data/' for success and 'errors/' for failure.
Why it's wrong here
Kinesis Data Firehose does not support dynamic prefixes based on record status within a single delivery stream. The error prefix is a separate configuration that applies only to records that fail transformation or delivery. Firehose automatically writes failed records to the error prefix if it is specified, but the prefix itself is static. You cannot use a dynamic prefix expression to route records based on their transformation result.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

Go deeper

DEA-C01 Data Operations and Support Practice Question

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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