The answer is to use DynamoDB on-demand capacity mode and DynamoDB auto scaling. On-demand mode eliminates the need to provision and pay for fixed read/write capacity, charging only for the actual operations performed, which directly addresses the challenge of reducing DynamoDB cost for unpredictable traffic by avoiding over-provisioning. Auto scaling complements this by dynamically adjusting provisioned capacity based on actual traffic patterns, ensuring you pay only for what you need without manual intervention. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this question tests your ability to differentiate between capacity modes under variable workloads; a common trap is selecting provisioned capacity with a high fixed limit, which would increase costs during low traffic. Remember the memory tip: “On-demand for the unpredictable, auto scaling for the variable”—if traffic is truly spiky and unknown, on-demand is the safest cost-saver, while auto scaling is best when you have a baseline but need elasticity.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO strategies can be used to reduce the cost of Amazon DynamoDB tables for a new application with unpredictable traffic patterns? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use DynamoDB auto scaling with provisioned capacity.
DynamoDB on-demand mode is ideal for unpredictable traffic, and auto scaling adjusts capacity based on load. Both help reduce costs compared to provisioned capacity with manual over-provisioning.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use DynamoDB auto scaling with provisioned capacity.
Why this is correct
Auto scaling adjusts capacity based on usage, preventing over-provisioning.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use DynamoDB Streams to reduce write capacity.
Why it's wrong here
Streams are used for change data capture, not for reducing capacity.
✗
Use DynamoDB global tables for multi-region replication.
Why it's wrong here
Global tables increase cost due to replication.
✗
Use DynamoDB Accelerator (DAX) to reduce read capacity.
Why it's wrong here
DAX is a caching layer that reduces read latency but does not directly reduce cost of the table; it adds cost.
✓
Use DynamoDB on-demand capacity mode.
Why this is correct
On-demand mode charges per request, suitable for unpredictable traffic.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
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
How to think about this question
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.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
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
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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 SAP-C02 NAT questions on configuration and troubleshooting.
Design for New Solutions — This question tests Design for New Solutions — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use DynamoDB auto scaling with provisioned capacity. — DynamoDB on-demand mode is ideal for unpredictable traffic, and auto scaling adjusts capacity based on load. Both help reduce costs compared to provisioned capacity with manual over-provisioning.
What should I do if I get this SAP-C02 question wrong?
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 SAP-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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