DBS-C01 Management and Operations Practice Question
A company has an Amazon RDS for SQL Server DB instance with Multi-AZ deployment. During a recent failover test, the application experienced a longer downtime than expected. The application uses a single connection string. What change should be made to reduce failover downtime?
⚠ Common exam trap
Watch out — candidates often think connection pooling (Option A) reduces failover downtime, but it actually addresses connection overhead, not DNS resolution delays, which is the primary cause of extended downtime during a Multi-AZ failover.
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
✓
Use a custom DNS CNAME record pointing to the RDS endpoint.
Using a custom DNS CNAME record that points to the RDS endpoint allows the application to control the DNS Time-To-Live (TTL) value independently. By setting a low TTL (e.g., 5 seconds) on the CNAME, the application's DNS resolver will refresh the IP address more quickly after a failover, reducing the time the application spends trying to connect to the old, unreachable primary instance. This minimizes downtime because the application can resolve the new primary's IP address sooner, rather than relying on the default RDS endpoint's TTL, which is typically set to 60 seconds and cannot be modified.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Implement connection pooling in the application.
Why it's wrong here
Connection pooling does not reduce failover time.
- ✓
Use a custom DNS CNAME record pointing to the RDS endpoint.
Why this is correct
CNAME allows DNS update after failover, reducing downtime.
- ✗
Set the DNS TTL to a higher value.
Why it's wrong here
Higher TTL increases DNS cache duration, potentially increasing downtime.
- ✗
Configure the application to use the RDS instance ID instead of endpoint.
Why it's wrong here
Instance ID is not a network address.
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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.