PAS-C01 Operations and Maintenance Practice Question
A company runs SAP on AWS and uses a Multi-AZ RDS for SAP ASE database. The operations team receives an alert that the database instance failed over automatically. After the failover, the SAP application servers are unable to connect to the database. The team checks the RDS console and sees that the DB instance status is 'available' and the endpoint is the same as before. The security groups and network ACLs have not changed. What is the MOST likely reason for 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
✓
The application servers have cached the old database IP address and need to flush DNS.
The RDS endpoint remains the same after a failover because the DNS record is updated to point to the new primary. However, the application servers may have cached the previous DNS resolution (old IP address). When the failover occurs, the application servers still try to connect to the old IP, which is no longer the primary. Flushing the DNS cache on the application servers resolves this issue. Option B is correct because the database endpoint DNS name does not change, but the IP address it resolves to changes; DNS caching prevents the application from connecting. Option A is incorrect because the endpoint does not change. Option C is incorrect because the DNS record is updated; the issue is client-side caching. Option D is incorrect because security groups remain unchanged after a 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.
- ✗
The RDS endpoint changed after the failover.
Why it's wrong here
The RDS endpoint DNS name remains the same after a Multi-AZ failover; only the underlying IP address changes. This option incorrectly suggests the endpoint changes.
- ✓
The application servers have cached the old database IP address and need to flush DNS.
Why this is correct
Correct. The application servers have cached the old IP address associated with the DNS name. Flushing the DNS cache on the application servers resolves the endpoint to the new IP, allowing connections to the new primary.
- ✗
The DNS record for the RDS endpoint did not update after the failover.
Why it's wrong here
The DNS record for the RDS endpoint is automatically updated by AWS during the failover to point to the new primary instance. This option is incorrect because the record does update.
- ✗
The security group for the database instance no longer allows traffic from the application servers.
Why it's wrong here
Security groups and network ACLs are not altered by the failover process. The existing rules remain in effect, so this is not the cause of the connectivity issue.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-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 PAS-C01 exam.