This DEA-C01 practice question tests your understanding of data operations and support. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A data engineer is troubleshooting a Kinesis Data Analytics application that processes streaming data. The application is falling behind, and the metric 'MillisBehindLatest' is consistently above 60000. The source Kinesis stream has 10 shards, and the application uses a Flink application with default parallelism. What is the MOST likely cause of the lag?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The sink (destination) is throttling writes.
Why wrong: The lag is measured at the source, not the sink.
The Flink application parallelism is set to 1.
Default parallelism of 1 causes a single consumer to process all shards.
The Kinesis stream has too few shards.
Why wrong: 10 shards is reasonable; the issue is parallelism.
The retention period of the Kinesis stream is too short.
Why wrong: Retention period does not cause lag.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The Flink application parallelism is set to 1.
Option C is correct because default parallelism in Flink is 1, which means only one task processes data from all shards, causing a bottleneck. Option A is wrong because increasing shards would increase parallelism but the issue is with parallelism. Option B is wrong because the retention period does not affect lag. Option D is wrong because the stream is the source, not the sink.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The sink (destination) is throttling writes.
Why it's wrong here
The lag is measured at the source, not the sink.
The Flink application parallelism is set to 1.
Why this is correct
Default parallelism of 1 causes a single consumer to process all shards.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
The Kinesis stream has too few shards.
Why it's wrong here
10 shards is reasonable; the issue is parallelism.
The retention period of the Kinesis stream is too short.
Why it's wrong here
Retention period does not cause lag.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
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FAQ
Data Operations and Support — This question tests Data Operations and Support — Static NAT maps one inside address to one outside address..
The correct answer is: The Flink application parallelism is set to 1. — Option C is correct because default parallelism in Flink is 1, which means only one task processes data from all shards, causing a bottleneck. Option A is wrong because increasing shards would increase parallelism but the issue is with parallelism. Option B is wrong because the retention period does not affect lag. Option D is wrong because the stream is the source, not the sink.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 20, 2026
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