SAA-C03 Design Resilient Architectures Practice Question
A company wants a disaster recovery setup for a web application. They want to keep costs low but still recover within a couple of hours after a regional disruption. They are willing to run only minimal infrastructure in the secondary location and scale it up during the outage. Which DR approach best matches this requirement?
⚠ Common exam trap
Test-takers frequently confuse Pilot light with Cold standby, as both involve minimal infrastructure, but Pilot light has core components already running (e.g., a small database instance) while Cold standby has nothing provisioned, leading to significantly longer recovery times.
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
✓
Pilot light, where the secondary Region keeps minimal core components ready and scales up during failover.
The Pilot light approach is correct because it keeps minimal core components (e.g., a small database, a scaled-down application server) running in the secondary Region, allowing rapid failover by scaling up those resources during an outage. This meets the requirement of low cost during normal operations while achieving recovery within a couple of hours, as the core infrastructure is already provisioned and can be scaled horizontally (e.g., using Auto Scaling groups and pre-configured AMIs) without needing to rebuild from scratch.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Active-active, where both Regions run full production at all times.
Why it's wrong here
Running full production simultaneously in two Regions is the most expensive DR pattern; it requires active-active traffic management, bidirectional data replication, and conflict-resolution logic for writes, so you pay for double capacity and ongoing operational complexity. For a target of a few hours RTO, this over-provisions — a warm standby pattern gives a much lower cost while still meeting the objective. It's not wrong because it can't fail, but because it's unnecessarily costly and complex for the stated requirement.
- ✓
Pilot light, where the secondary Region keeps minimal core components ready and scales up during failover.
Why this is correct
Pilot light keeps a minimal but always-on core in the secondary Region — for example, an RDS cross-Region read replica or replicated DynamoDB tables — while application servers and other scale-out components stay shut down. On failover, you use pre-built AMIs or CloudFormation templates to quickly scale up the remaining infrastructure, change Route 53 routing, and start serving traffic. This gives a low RTO (often under an hour) and lower steady-state cost than active-active, making it the best fit for the stated couple-hour RTO.
- ✗
Cold standby, where no infrastructure is running in the secondary Region until an outage occurs.
Why it's wrong here
Cold standby has no infrastructure running in the secondary Region; even the database must be restored or built from scratch during an outage. While it is the cheapest option at steady state, the RTO is driven by how long it takes to provision EC2 instances, restore data, configure load balancers, and test the environment — often hours to days. Without pre-staged, automated deployment tooling, that manual effort routinely misses a couple-hour recovery window.
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Backups-only, where recovery relies solely on manually restoring snapshots during an outage.
Why it's wrong here
Backups-only treats DR as a data-restore exercise: you must manually restore EBS snapshots or RDS backups, then rebuild the compute and network layers and hope the restored data is consistent. This approach can satisfy an RPO but fails the stated RTO because every step is manual and the environment isn't pre-defined. Even with orchestration, it doesn't address the full application topology, so it is not a credible DR strategy for a web app that must come back in a few hours.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAA-C03 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 SAA-C03 exam.