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Difficulty: MediumHigh Availability and Disaster Recovery Design

A retail company is designing a new multi-region web application across two AWS Regions: us-east-1 (primary) and us-west-2 (secondary) to host its e-commerce portal. To maintain high availability, the architecture must support a recovery time objective (RTO) of less than 15 minutes and a recovery point objective (RPO) of less than 1 minute. Users must be routed to the closest Region to minimize latency. Additionally, backend instances in private subnets must connect to external payment gateways on the internet with maximum availability and no single point of failure in any Availability Zone. Which two actions should the solutions architect take to meet these requirements? (Select two.)

  1. Configure Amazon Route 53 latency-based routing with active-active failover by associating the latency records for both Regions with Route 53 health checks that monitor the Application Load Balancers.Answer
  2. Deploy a NAT Gateway in each Availability Zone in both Regions, and configure the private subnet route tables to route outbound internet traffic through the local NAT Gateway in their respective zones.Answer
  3. C
    Deploy a single NAT Gateway in one Availability Zone in each Region, and configure the route tables of all private subnets across all Availability Zones in that Region to route outbound internet traffic through this single NAT Gateway.
  4. D
    Configure Route 53 latency-based routing to the Application Load Balancers, but disable the evaluate target health setting on the records to prevent DNS routing changes during transient health check failures.
  5. E
    Configure Amazon Aurora PostgreSQL with a cross-Region Read Replica in the secondary Region, and set up a custom AWS Lambda function to capture daily EBS snapshots of the database to meet the 1-minute RPO.
  6. F
    Configure a Route 53 Private Hosted Zone for internal API resolution and associate it only with the VPC in us-east-1, relying on active transit gateways for automatic DNS propagation to the secondary Region.

Answer

Configure Amazon Route 53 latency-based routing with active-active failover using health checks for regional ALBs, and deploy zone-redundant NAT Gateways in each Availability Zone in both Regions for high availability.
To satisfy the low latency and active-active failover requirements, Route 53 latency-based routing must be paired with health checks. This ensures that users are directed to the nearest healthy Region and automatically rerouted during an outage, maintaining the RTO of under 15 minutes. To prevent outbound network single points of failure, a dedicated NAT Gateway must be configured in each Availability Zone where backend instances reside.

Step-by-Step Solution

1
Evaluate the routing requirement for low latency and high availability.
Determine that Amazon Route 53 latency-based routing with health checks enabled is required to send traffic to the nearest healthy Region and automatically fail over.
This configuration meets the active-active multi-region requirement and satisfies the recovery time objective (RTO) under 15 minutes.
2
Evaluate the outbound connectivity requirements for high availability.
Determine that deploying a NAT Gateway in each Availability Zone within each Region is necessary to prevent a single point of failure.
If a single NAT Gateway is deployed per Region, an Availability Zone outage affecting that gateway would break outbound internet connectivity for instances in all other zones.
3
Analyze the data recovery objective constraints.
Identify that daily snapshots fail to meet the RPO of less than 1 minute, requiring continuous replication methods instead.
This rules out solutions that rely on manual or daily snapshot processes.

Key Concept

Designing high availability and disaster recovery architectures with multi-region routing policies and redundant networking paths.
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Topics

High Availability and Disaster Recovery Design

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