Question #1546
A company operates a global e-commerce platform using a single AWS Region. The architecture includes web servers and application servers on Amazon EC2 instances within Auto Scaling groups behind Elastic Load Balancers. The platform uses an Amazon Aurora global database cluster spanning multiple Availability Zones. The company wants to ensure maximum fault tolerance and minimal downtime during regional outages.
Which solution provides the MOST fault tolerance?
Extend the Auto Scaling groups for the web and application tiers to deploy instances in a second Region. Use an Aurora global database in both Regions. Configure Amazon Route 53 with health checks and a failover routing policy to direct traffic to the second Region during outages.
Deploy the web and application tiers to a second Region. Create a cross-Region Aurora Replica in the second Region. Use Amazon Route 53 health checks with a failover routing policy to the second Region. Manually promote the secondary database to primary during failover.
Deploy the web and application tiers to a second Region. Provision a new Aurora PostgreSQL database in the second Region. Use AWS Database Migration Service (AWS DMS) for continuous replication between the primary and secondary Regions. Configure Route 53 with a failover routing policy.
Deploy the web and application tiers to a second Region. Use an Aurora global database spanning both Regions. Configure Amazon Route 53 with health checks and a failover routing policy to the second Region. Promote the secondary database to primary during regional outages.
Explanation
Option D provides the MOST fault tolerance by:
1. Deploying web/application tiers in a second Region for compute redundancy.
2. Using an Aurora global database, which natively supports cross-Region replication with <1-second replication lag and allows rapid promotion of the secondary Region to primary.
3. Configuring Route 53 with health checks and failover routing for automatic traffic redirection.
Why other options are inferior:
- A: Aurora global databases already span Regions; deploying duplicate clusters in both Regions is redundant.
- B: Manual promotion of cross-Region replicas introduces delays and human error risks.
- C: AWS DMS replication is less efficient than Aurora's native replication and requires additional management.
Key points:
- Aurora global databases enable low-latency cross-Region replication and fast failover.
- Route 53 failover routing automates traffic redirection during outages.
- Multi-Region deployments with Auto Scaling ensure compute redundancy.
Answer
The correct answer is: D