The answer is insufficient provisioned read capacity on the GSI caused by hot partitions. This is correct because when a global secondary index uses a composite key like (status, current_bid), a skewed workload—such as many active auctions with similar high current_bid values—concentrates reads on a single partition, throttling that partition even if the GSI’s total 5,000 RCU is underutilized. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding that DynamoDB throttles at the partition level, not the table or index level, and that provisioned capacity is distributed evenly across partitions; a common trap is assuming total RCU is the bottleneck when the real issue is uneven access patterns. Remember the memory tip: “Hot partition, cold rest—throttling hits the busiest nest.”
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 runs an online auction platform on AWS. The application uses Amazon DynamoDB as the primary database, with a table 'Auctions' that has a partition key 'auction_id' (String) and sort key 'end_time' (Number). The table also has a global secondary index (GSI) on 'status' (String) and 'current_bid' (Number). The application frequently queries for active auctions sorted by current bid. Recently, the team noticed that queries on the GSI for active auctions with a high current_bid are returning results slowly. The DynamoDB table has 10,000 write capacity units (WCU) and 30,000 read capacity units (RCU) provisioned. The GSI has 5,000 RCU provisioned. The team suspects throttling on the GSI. What is the most likely cause of the slow queries?
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.
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
✓
The GSI's provisioned RCU is insufficient due to hot partitions.
Option C is correct because if the index key (status, current_bid) leads to hot partitions (e.g., many active auctions with similar current_bid), those partitions may be throttled even if overall provisioned RCU is not fully utilized. Option A is wrong because the table RCU is high, but index RCU is separate. Option B is wrong because there's no indication of WCU throttling for reads. Option D is wrong because the index key design is not necessarily wrong; hot partitions cause throttling.
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.
✓
The GSI's provisioned RCU is insufficient due to hot partitions.
Why this is correct
Hot partitions can throttle even if total RCU is not fully used.
Clue confirmation
The clue words "most likely", "primary" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The GSI key schema is inefficient for the query pattern.
Why it's wrong here
The schema is appropriate; throttling is the issue.
✗
The table's WCU is too low, causing throttling on writes that affects reads.
Why it's wrong here
Write throttling does not directly cause read throttling on index.
✗
The table's RCU is too low for the application's read load.
Why it's wrong here
Table RCU is separate from index RCU.
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 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
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: The GSI's provisioned RCU is insufficient due to hot partitions. — Option C is correct because if the index key (status, current_bid) leads to hot partitions (e.g., many active auctions with similar current_bid), those partitions may be throttled even if overall provisioned RCU is not fully utilized. Option A is wrong because the table RCU is high, but index RCU is separate. Option B is wrong because there's no indication of WCU throttling for reads. Option D is wrong because the index key design is not necessarily wrong; hot partitions cause throttling.
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: "most likely", "primary". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Amazon DynamoDB for a shopping cart application. During a flash sale, write requests are throttled due to hot partitions. The access pattern is evenly distributed across items, but the partition key is the customer ID. Which design change would best mitigate throttling?
hard
✓ A.Enable DynamoDB adaptive capacity.
B.Change the partition key to a single value for all items.
C.Increase the provisioned write capacity to a higher fixed value.
D.Add a DAX cluster in front of DynamoDB.
Why A: Option A is correct because DynamoDB adaptive capacity automatically adjusts throughput capacity based on traffic patterns, which helps mitigate hot partitions by redistributing unused capacity from less-accessed partitions to heavily accessed ones. This is ideal for the flash sale scenario where write requests are throttled due to uneven access across customer ID partitions, even though the overall access pattern is evenly distributed.
Last reviewed: Jun 20, 2026
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This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.
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