DBS-C01 Storage Auto-scaling Practice Question
A company's Amazon RDS for PostgreSQL instance is running out of storage. The DB instance has auto-scaling enabled, but the storage did not increase. What is the most likely cause?
⚠ Common exam trap
Candidates often confuse 'maximum storage threshold' with 'allocated storage'. The threshold is the upper limit for auto-scaling; once reached, no further scaling occurs.
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
✓
The DB instance has exceeded the Maximum Storage Duration setting.
Amazon RDS storage auto-scaling will not increase storage beyond the maximum storage threshold set by the user. If the instance has reached this maximum threshold, auto-scaling stops, even if free space is low. The phrase 'Maximum Storage Duration' in the option refers to this threshold. Option D is incorrect because the condition for auto-scaling is based on free space being below 10%, not on whether the maximum storage has been reached. If the maximum threshold has not been reached, auto-scaling should occur when free space is low.
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 DB instance class does not support storage auto-scaling.
Why it's wrong here
Many DB instance classes support storage auto-scaling, provided the instance is in a VPC and not a legacy class.
- ✗
The DB instance is smaller than the minimum storage size for auto-scaling.
Why it's wrong here
There is no minimum storage size for auto-scaling; it works with any supported storage type.
- ✓
The DB instance has exceeded the Maximum Storage Duration setting.
Why this is correct
As the most likely cause is that the maximum storage threshold has been reached, preventing further auto-scaling.
- ✗
The storage usage has not reached the maximum allocated storage.
Why it's wrong here
If storage usage has not reached the maximum allocated storage (i.e., free space is above 10%), auto-scaling would not trigger, but the question states the instance is running out of storage, implying free space is low. Auto-scaling should occur unless the maximum threshold is reached.
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JA
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.