DBS-C01 Management and Operations Practice Question
A company is running an Amazon RDS for MySQL instance with Multi-AZ. The primary instance in us-east-1a fails, and the standby in us-east-1b is promoted. The application cannot connect after failover. Which TWO steps should the database administrator take to restore connectivity?
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
✓
Update the application's connection string to point to the new writer endpoint.
After failover, the application may be connecting to the old primary instance endpoint. Updating the connection string to the DNS writer endpoint (which automatically points to the new primary) ensures connectivity. Option D is correct because after failover, the writer endpoint's DNS record updates to the new primary's IP. Waiting for propagation and flushing the DNS cache ensures the application resolves the updated IP. Option B is incorrect because rebooting is not required and would cause further disruption. Option C is incorrect because the security group already permits traffic from the application; the issue is DNS resolution, not network access. Option E is incorrect because creating a read replica does not solve the connectivity issue and is unnecessary for a Multi-AZ failover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Update the application's connection string to point to the new writer endpoint.
Why this is correct
Explicitly updating the endpoint ensures immediate connectivity.
- ✗
Reboot the new primary instance to reset connections.
Why it's wrong here
Rebooting causes additional downtime and is unnecessary.
- ✗
Update the security group to allow inbound traffic from the application.
Why it's wrong here
Security group configuration remains valid after failover.
- ✓
Wait for DNS propagation and flush the application's DNS cache.
Why this is correct
DNS changes propagate automatically; flushing cache speeds up resolution.
- ✗
Create a read replica and promote it to a new primary.
Why it's wrong here
Creating a read replica is unnecessary; a primary already exists.
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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.