DEA-C01 DynamoDB capacity modes Practice Question
A company has an Amazon DynamoDB table with a provisioned write capacity of 1000 WCU. During a flash sale, the write traffic spikes to 5000 WCU for 10 minutes. The table is not auto-scaled. Which action should the data engineer take to handle the spike without throttling?
⚠ Common exam trap
Candidates often assume DAX can handle write spikes because it is a cache, but DAX only caches reads and does not buffer writes. The correct approach is to use on-demand capacity for unpredictable traffic spikes.
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
✓
Convert the table to on-demand capacity mode before the sale.
The table is currently provisioned with 1000 WCU and cannot handle a spike to 5000 WCU. Converting to on-demand mode before the sale allows DynamoDB to automatically handle varying traffic without throttling, as on-demand capacity scales instantly to meet demand. Option D (auto-scaling) might not react quickly enough for a short 10-minute spike, and the table is not currently auto-scaled. Option C is incorrect because DAX is a read cache and does not buffer or improve write capacity. Option B is reactive and would not prevent initial throttling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Convert the table to on-demand capacity mode before the sale.
Why this is correct
Correct. By converting to on-demand capacity mode, the table automatically scales to handle any write traffic without throttling. This is the most reliable way to handle a temporary spike.
- ✗
Set a CloudWatch alarm to increase provisioned capacity when write throttling occurs.
Why it's wrong here
Incorrect. Setting a CloudWatch alarm is reactive; it only triggers an action after throttling has occurred, leading to potential data loss or delays.
- ✗
Use DynamoDB Accelerator (DAX) to cache writes.
Why it's wrong here
Incorrect. DAX is a read-only cache that improves read performance but does not affect write capacity or buffering. It cannot handle write spikes.
- ✗
Enable auto-scaling with a target utilization of 70% and a maximum capacity of 5000 WCU.
Why it's wrong here
Incorrect. While auto-scaling can increase capacity, it may take several minutes to scale, so a short 10-minute spike might still experience throttling before scaling completes. On-demand is more immediate.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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