The answer is TTL, DAX, and Point-in-time recovery (PITR). TTL automatically expires stale session data, reducing table size and improving query performance by keeping the working set lean. DAX provides an in-memory cache that delivers microsecond read latency, dramatically accelerating repeated access to session records. PITR enables continuous backups to restore the table to any point within the last 35 days, safeguarding against accidental writes or deletions. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your ability to distinguish between features that genuinely enhance performance and durability versus those that are irrelevant for on-demand capacity—a common trap is selecting auto scaling, which only applies to provisioned mode. Remember the mnemonic “TDP”: TTL for cleanup, DAX for speed, PITR for safety.
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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 deploying a new Amazon DynamoDB table with on-demand capacity. The table will store session data for a web application. Which THREE features should be enabled to improve performance and durability?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Auto scaling
Auto scaling is correct because DynamoDB on-demand capacity automatically scales throughput based on traffic patterns, eliminating the need for manual capacity management. However, the question asks for features to improve performance and durability, and auto scaling is not applicable to on-demand tables (it is for provisioned mode). For on-demand, throughput adjusts instantly, so auto scaling is irrelevant and should not be selected. The correct features for performance and durability are TTL (to automatically expire old session data, reducing storage costs and improving query performance), DAX (to provide in-memory caching for microsecond read latency), and PITR (to protect against accidental writes or deletes by enabling continuous backups).
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.
✓
Auto scaling
Why this is correct
Auto scaling adjusts capacity to handle traffic spikes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Time to Live (TTL)
Why it's wrong here
TTL automatically expires old items, but does not improve performance or durability.
✓
DynamoDB Accelerator (DAX)
Why this is correct
DAX improves read performance with caching.
Related concept
Read the scenario before looking for a memorised answer.
✓
Point-in-time recovery (PITR)
Why this is correct
PITR provides durability by allowing restores to any point in time.
Related concept
Read the scenario before looking for a memorised answer.
✗
Global tables
Why it's wrong here
Global tables are for multi-region active-active, not performance in one region.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume auto scaling is always beneficial for performance, but DynamoDB on-demand mode already handles scaling automatically, making auto scaling redundant and incorrect for this scenario.
Detailed technical explanation
How to think about this question
DynamoDB on-demand mode uses a credit-based burst pool and scales instantly to accommodate traffic spikes, but it does not support auto scaling policies. TTL works by timestamping items and deleting them within 48 hours of expiry, which keeps the table lean and reduces read/write costs. DAX is a write-through caching cluster that offloads read traffic from the main table, reducing latency from single-digit milliseconds to microseconds for hot data. PITR enables continuous backups with 35-day granularity, allowing restoration to any point within that window, which is critical for durability against accidental data loss.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Auto scaling — Auto scaling is correct because DynamoDB on-demand capacity automatically scales throughput based on traffic patterns, eliminating the need for manual capacity management. However, the question asks for features to improve performance and durability, and auto scaling is not applicable to on-demand tables (it is for provisioned mode). For on-demand, throughput adjusts instantly, so auto scaling is irrelevant and should not be selected. The correct features for performance and durability are TTL (to automatically expire old session data, reducing storage costs and improving query performance), DAX (to provide in-memory caching for microsecond read latency), and PITR (to protect against accidental writes or deletes by enabling continuous backups).
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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Question Discussion
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