- A
Create an AWS Lambda function that runs every hour and deletes expired session data
Why wrong: Lambda-based deletion is possible but add complexity and potential cost, and is not the simplest design.
- B
Store session data in Amazon S3 with a lifecycle policy to delete objects after 24 hours
Why wrong: S3 can handle session data but does not provide the required single-digit millisecond latency for session token lookups.
- C
Use DynamoDB Accelerator (DAX) to cache session data and set a 24-hour TTL on the cache
Why wrong: DAX is an in-memory cache that can improve latency but does not automatically delete items from the DynamoDB table.
- D
Enable DynamoDB Time to Live (TTL) on the session token attribute
TTL automatically deletes items after a specified expiry timestamp, meeting the 24-hour deletion requirement.
Quick Answer
The correct choice is to enable DynamoDB Time to Live (TTL) on the session token attribute. This works because TTL automatically deletes expired items based on a timestamp you define, so session data older than 24 hours is removed without any additional code or infrastructure, while using the session token as the primary key ensures single-digit millisecond latency for lookups. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of cost-effective, serverless data lifecycle management—a common trap is to propose a separate cleanup job or a secondary index, which adds complexity and latency. Remember that TTL is a native DynamoDB feature that handles expiration at no extra cost, making it the ideal solution for temporary session data. A helpful memory tip: “TTL trims the table without a timer—just set the timestamp and forget the cleanup script.”
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 is designing a new e-commerce platform using Amazon DynamoDB. The workload requires single-digit millisecond latency for user session data, which is accessed by session token. The session data is temporary and should be automatically deleted after 24 hours. Which DynamoDB design should the database specialist recommend?
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
Enable DynamoDB Time to Live (TTL) on the session token attribute
DynamoDB Time to Live (TTL) automatically deletes expired items after a specified timestamp, making it ideal for session data that must be removed after 24 hours. This approach requires no additional infrastructure, meets the single-digit millisecond latency requirement by using the session token as the primary key, and ensures automatic cleanup without manual intervention or added cost.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create an AWS Lambda function that runs every hour and deletes expired session data
Why it's wrong here
Lambda-based deletion is possible but add complexity and potential cost, and is not the simplest design.
- ✗
Store session data in Amazon S3 with a lifecycle policy to delete objects after 24 hours
Why it's wrong here
S3 can handle session data but does not provide the required single-digit millisecond latency for session token lookups.
- ✗
Use DynamoDB Accelerator (DAX) to cache session data and set a 24-hour TTL on the cache
Why it's wrong here
DAX is an in-memory cache that can improve latency but does not automatically delete items from the DynamoDB table.
- ✓
Enable DynamoDB Time to Live (TTL) on the session token attribute
Why this is correct
TTL automatically deletes items after a specified expiry timestamp, meeting the 24-hour deletion requirement.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse DynamoDB TTL with a feature that provides real-time or immediate deletion, when in fact TTL deletes items asynchronously in the background, typically within a few minutes to 48 hours, which is acceptable for temporary session data but not for compliance-driven immediate removal.
Detailed technical explanation
How to think about this question
DynamoDB TTL works by evaluating the TTL attribute (a Unix epoch timestamp in seconds) and typically deletes expired items within 48 hours of expiration, though most deletions occur within minutes. For session data requiring precise 24-hour expiry, the session token attribute should be used as the primary key, and a separate TTL attribute (e.g., 'expireAt') should store the deletion timestamp. This design ensures that the session token directly retrieves the item with single-digit millisecond latency, while TTL handles background cleanup without impacting read or write performance.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
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FAQ
Questions learners often ask
What does this DBS-C01 question test?
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable DynamoDB Time to Live (TTL) on the session token attribute — DynamoDB Time to Live (TTL) automatically deletes expired items after a specified timestamp, making it ideal for session data that must be removed after 24 hours. This approach requires no additional infrastructure, meets the single-digit millisecond latency requirement by using the session token as the primary key, and ensures automatic cleanup without manual intervention or added cost.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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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