SOA-C02 Reliability and Business Continuity Practice Question
A company has an application that runs on EC2 instances behind an Application Load Balancer. The application uses an RDS Multi-AZ database. The company wants to ensure that the application remains available during a database failover. What should the SysOps administrator do?
⚠ Common exam trap
Many candidates confuse high-availability infrastructure (Multi-AZ, termination protection) with application-level resilience, assuming the infrastructure alone guarantees uptime without requiring the application to handle transient connection failures.
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
✓
Ensure the application retries database connections during failover.
During an RDS Multi-AZ failover, the database DNS record is updated to point to the standby instance, which can take up to 60 seconds. Existing connections are dropped, so the application must implement connection retry logic with exponential backoff to re-establish connections to the new primary. Without retries, the application will fail to serve requests until the database is reachable again, breaking availability.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Ensure the application retries database connections during failover.
Why this is correct
During a Multi-AZ RDS failover, the RDS DNS CNAME is repointed to the standby database, a process that typically takes 60–120 seconds, during which existing database connections are forcibly terminated. A resilient application must catch connection errors and retry with exponential backoff or a fresh connection attempt so it can ride through the interruption; without this retry logic, requests that arrive during the failover window will return errors even after the new primary is ready.
- ✗
Create a read replica of the database to offload read traffic.
Why it's wrong here
A read replica is designed to offload SELECT traffic and improve read scalability for a database, but it operates asynchronously and cannot accept writes or be promoted for Multi-AZ automatic failover. The primary database remains the only writable endpoint during a failover event, so adding a read replica does not help the application maintain write availability or recover from a primary outage; it is not a failover or high-availability mechanism.
- ✗
Increase the EC2 instance size to handle the load.
Why it's wrong here
Modifying the EC2 instance size changes only the vCPU, memory, and network capacity of your application servers, none of which affects how the database handles failover or whether the database endpoint is available. If the underlying RDS instance is undergoing a Multi-AZ failover, the application will still receive connection refused or timeout errors regardless of how large the EC2 instances are; vertical scaling of the compute tier does not address database-side availability.
- ✗
Enable termination protection on the EC2 instances.
Why it's wrong here
Termination protection on EC2 instances prevents accidental deletion of the instance itself through the EC2 API, but it has no effect on database connections, database failover behavior, or the RDS endpoint. The database availability issue referenced in this question is unrelated to EC2 lifecycle protections, so enabling this setting would not prevent the application from failing when the primary database becomes temporarily unreachable during failover.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-C02 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 SOA-C02 exam.