DEA-C01 Data Ingestion and Transformation Practice Question
A data engineer is designing a streaming pipeline using Amazon Kinesis Data Streams with a shard count of 10. The incoming data rate is 1 MB/second. The consuming application uses the Kinesis Client Library (KCL) with a single worker. What is the most likely performance bottleneck?
⚠ Common exam trap
Many candidates assume the bottleneck is on the write side (insufficient shards or write capacity) because they focus on the incoming data rate, but the question specifically tests the consumer-side limitation of a single KCL worker unable to parallelize across multiple shards.
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
✓
The single KCL worker cannot process all shards in parallel
The Kinesis Client Library (KCL) uses a 1:1 mapping between shards and record processors by default. With 10 shards and only a single KCL worker, that worker must run all 10 record processors sequentially on a single host, creating a bottleneck. The worker cannot process records from multiple shards in parallel, so the throughput is limited by the single worker's processing capacity, not the stream's write capacity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The Lambda function invoked by the stream has a cold start issue
Why it's wrong here
The scenario uses KCL, not Lambda.
- ✗
The data stream has insufficient write capacity
Why it's wrong here
Kinesis Data Streams uses shard-based throughput, not write capacity units.
- ✓
The single KCL worker cannot process all shards in parallel
Why this is correct
KCL workers should be scaled to match shard count for parallel processing.
- ✗
The shard count is too low to handle the data rate
Why it's wrong here
10 shards can handle up to 10 MB/s ingestion, so the shard count is sufficient.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DEA-C01 exam.