DBS-C01 Workload-Specific Database Design Practice Question
A company uses Amazon DynamoDB for a session management system. They need to store session data with a TTL of 24 hours. However, they notice that expired items are not being deleted promptly, causing storage costs to increase. What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume TTL deletions are instantaneous or happen within minutes, but AWS explicitly documents a 48-hour window, making delayed deletion the expected behavior rather than a misconfiguration.
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
✓
DynamoDB typically deletes expired items within 48 hours
DynamoDB's TTL mechanism typically deletes expired items within 48 hours, not immediately. The service processes TTL deletions as a background process, and while items are marked as expired at the TTL time, actual deletion can be delayed up to 48 hours. This explains why expired session data persists and increases storage costs despite TTL being properly configured.
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 table has insufficient write capacity
Why it's wrong here
TTL deletions are processed in the background and do not consume write capacity.
- ✗
TTL is not enabled on the table
Why it's wrong here
TTL is enabled per table, not per item.
- ✓
DynamoDB typically deletes expired items within 48 hours
Why this is correct
TTL deletions are eventually consistent and can take up to 48 hours.
- ✗
The TTL attribute is set as a string instead of a number
Why it's wrong here
TTL attribute must be a number (epoch time). String values cause TTL to not work.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.