DEA-C01 Data Store Management Practice Question
A data engineer is setting up an Amazon DynamoDB table to store user session data. The table must handle sudden spikes in read traffic during peak hours, and the engineer wants to minimize operational overhead while ensuring consistent performance. The table's read capacity mode should automatically adjust to traffic changes. Which capacity mode should the engineer choose?
⚠ Common exam trap
The trap here is assuming that provisioned mode with auto scaling is equivalent to on-demand; auto scaling has a delay and requires configuration, while on-demand provides immediate, automatic scaling.
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
✓
On-demand capacity mode.
On-demand capacity mode is designed for workloads with unpredictable traffic patterns. It automatically scales to handle sudden spikes in read and write traffic, eliminating the need for capacity planning and reducing operational overhead. This makes it the best choice for session data with variable demand.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
On-demand capacity mode.
Why this is correct
On-demand capacity mode automatically scales read and write capacity to handle traffic changes without requiring any capacity planning. It instantly accommodates sudden spikes in traffic and charges per request, making it ideal for unpredictable workloads with minimal operational overhead. This directly meets the requirement for automatic adjustment and consistent performance.
- ✗
Provisioned capacity mode with global secondary indexes.
Why it's wrong here
Global secondary indexes are used to enable queries on non-primary key attributes, but they do not affect the table's capacity mode. They still consume read/write capacity and require provisioning if the table is in provisioned mode. This option does not address the need for automatic capacity adjustment.
- ✗
Provisioned capacity mode with auto scaling enabled.
Why it's wrong here
Provisioned mode with auto scaling can adjust capacity based on utilization, but it requires configuring scaling policies and has a delay in responding to sudden spikes. It also may not scale as quickly as on-demand mode. While it reduces operational overhead compared to manual provisioning, it still requires some management and may not provide immediate responsiveness for unpredictable spikes.
- ✗
Provisioned capacity mode with reserved capacity.
Why it's wrong here
Reserved capacity provides cost savings for steady-state workloads by reserving a certain amount of capacity for a term, but it does not automatically adjust to traffic changes. It requires upfront planning and commitment, which is not suitable for sudden spikes. It also adds operational overhead for managing reservations.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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