Question 1,482 of 1,711
DEA-C01 Data Store Management Practice Question
A company is using Amazon RDS for MySQL with Multi-AZ deployment. The primary DB instance experiences a hardware failure, causing automatic failover to the standby. After the failover, the application reports that the database endpoint is unreachable for about 60 seconds. What is the MOST likely cause?
⚠ Common exam trap
A common mix-up: candidates assume the standby promotion itself causes the delay, but AWS specifically designs the promotion to be fast, and the real bottleneck is DNS propagation and client caching.
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 DNS record for the DB instance endpoint needed to update to point to the new primary.
After an automatic failover in Amazon RDS Multi-AZ, the DNS record for the DB instance endpoint is updated to point to the new primary. This DNS change can take up to 60 seconds to propagate, during which the application may receive 'unreachable' errors if it caches the old DNS resolution. The 60-second outage aligns with the typical TTL (Time To Live) of 30 seconds for RDS DNS records plus propagation delays.
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 standby instance took longer than expected to promote to primary.
Why it's wrong here
RDS failover typically completes within 60-120 seconds, matching the outage.
- ✗
The standby instance was not in a synchronized state and required a manual promotion.
Why it's wrong here
RDS automatically promotes the standby without manual intervention.
- ✗
The application was using the wrong endpoint and needed to be reconfigured.
Why it's wrong here
The endpoint remains the same after failover.
- ✓
The DNS record for the DB instance endpoint needed to update to point to the new primary.
Why this is correct
DNS propagation causes the 60-second delay.
Visual reference
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Last reviewed: Jul 4, 2026
This DEA-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 DEA-C01 exam.
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