DBS-C01 Monitoring and Troubleshooting Practice Question
A company uses Amazon RDS for PostgreSQL with Multi-AZ deployment. The primary instance fails, and a failover occurs. After the failover, the application is still unable to connect to the database endpoint. The database administrator checks the RDS console and sees that the new primary is in 'available' state. What should the administrator do next to diagnose the connectivity issue?
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
✓
Check the DNS resolution of the RDS endpoint from the application server
The DNS CNAME of the RDS endpoint should have updated to point to the new primary. If the application is using the old IP or a cached DNS entry, it may not connect. Option A is incorrect because security group rules are usually unchanged. Option B is incorrect because the subnet group is not the issue. Option D is incorrect because the primary is already in available state.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Verify that the security group for the RDS instance allows inbound traffic from the application
Why it's wrong here
Security groups are still in place and usually unchanged after failover.
- ✗
Check if the subnet group for the RDS instance is correctly configured
Why it's wrong here
Subnet groups are not affected by failover.
- ✓
Check the DNS resolution of the RDS endpoint from the application server
Why this is correct
The CNAME record should be updated; stale DNS could cause connection failures.
- ✗
Restart the RDS instance to force a new connection
Why it's wrong here
Restarting is unnecessary and may cause further downtime.
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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.