DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. 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.
A company uses Amazon DynamoDB to store order data. The table has a primary key (OrderID) and a Global Secondary Index (GSI) on CustomerID. The application often queries for all orders of a customer sorted by order date. The GSI projects only the keys. The queries are slow. What should the team do to improve query performance? (Choose two.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the GSI to include OrderDate as a sort key
Option B: Adding a sort key (OrderDate) to the GSI allows sorting natively. Option D: If the GSI projects only keys, each query results in a fetch from the base table (expensive). Changing projection to INCLUDE or ALL avoids the extra fetch. Option A would increase write costs unnecessarily. Option C may not help if the GSI is inefficient. Option E is not directly related.
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.
✗
Enable DynamoDB Accelerator (DAX) for the table
Why it's wrong here
DAX caches data but does not help with sorting or projection issues.
✗
Increase the read capacity of the GSI
Why it's wrong here
Increasing read capacity may reduce throttling but does not address the root cause of slow queries.
✓
Modify the GSI to include OrderDate as a sort key
Why this is correct
Adding OrderDate as a sort key allows the GSI to return items sorted by order date without additional processing.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use a Local Secondary Index (LSI) instead of a GSI
Why it's wrong here
LSI requires the same partition key as the table (OrderID), not CustomerID.
✓
Change the GSI projection to include all attributes
Why this is correct
Projecting all attributes avoids fetching from the base table, reducing latency.
Clue confirmation
The clue word "primary" in the question point toward this answer.
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 DBS-C01 NAT questions on configuration and troubleshooting.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Modify the GSI to include OrderDate as a sort key — Option B: Adding a sort key (OrderDate) to the GSI allows sorting natively. Option D: If the GSI projects only keys, each query results in a fetch from the base table (expensive). Changing projection to INCLUDE or ALL avoids the extra fetch. Option A would increase write costs unnecessarily. Option C may not help if the GSI is inefficient. Option E is not directly related.
What should I do if I get this DBS-C01 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 DBS-C01 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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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