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Difficulty: MediumHigh Availability and Disaster Recovery Design

A company is designing a high-availability telemetry processing system for a regional electric vehicle (EV) charging network. The application tier runs on Amazon EC2 instances in an Auto Scaling group across multiple Availability Zones, positioned behind an Application Load Balancer (ALB). The database tier uses Amazon Aurora PostgreSQL. The design requirements specify a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 2 minutes. Outbound communications from the EC2 instances to external third-party APIs must remain highly available even during local network device failures. In the event of a regional disaster, the application must fail over to a secondary AWS region with minimal manual intervention. Which two options should the solutions architect choose to meet these requirements? (Select two.)

  1. Deploy an Amazon Aurora Global Database with the primary DB cluster in the active region and a secondary DB cluster in the disaster recovery region to achieve sub-minute data replication.Answer
  2. Deploy a NAT Gateway in each Availability Zone within the active region, and update the route tables of the private subnets in each zone to point outbound traffic to the NAT Gateway in their corresponding zone.Answer
  3. C
    Configure a single NAT Gateway in the primary Availability Zone of the active region, routing outbound traffic from all private subnets through this gateway to consolidate outbound traffic and reduce running costs.
  4. D
    Implement a backup and restore strategy by scheduling hourly manual snapshots of the Aurora DB cluster, copying the snapshots to the secondary region, and restoring them during a regional failover.
  5. E
    Create a Route 53 Private Hosted Zone for internal API resolution in the active region's VPC, and establish a VPC peering connection to the secondary region's VPC to automatically enable resolution of the private DNS names without associating the zone with the secondary VPC.

Answer

Deploying an Amazon Aurora Global Database with a secondary DB cluster in the disaster recovery region, and deploying a NAT Gateway in each Availability Zone with local route configurations.
Deploying an Amazon Aurora Global Database provides physical replication to a secondary region with sub-second lag, satisfying the 2-minute RPO. Promoting this secondary cluster handles failovers within the 15-minute RTO. Additionally, deploying separate NAT Gateways in each Availability Zone prevents a single Availability Zone outage from disrupting outbound network traffic for the remaining zones.

Step-by-Step Solution

1
Evaluate the database replication strategy against the 2-minute RPO constraint.
Amazon Aurora Global Database replication occurs at the storage layer with typical lag of less than 1 second, meeting the 2-minute RPO requirement, whereas snapshot restoration has an RPO of up to 1 hour.
Ensuring the selected replication mechanism matches the target data loss threshold.
2
Evaluate outbound traffic routing for high availability.
A multi-AZ application tier requires localized NAT Gateways in each Availability Zone so that an outage in one zone does not disrupt outbound traffic originating from other zones.
Eliminating single points of failure in outbound network pathing.
3
Assess the internal DNS name resolution requirements across VPC boundaries.
Route 53 Private Hosted Zones require explicit association with target VPCs across peered networks to resolve internal DNS names.
Ensuring cross-region service connectivity behaves as expected.

Key Concept

Designing multi-region disaster recovery and multi-Availability Zone high availability configurations on AWS.
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Topics

High Availability and Disaster Recovery Design

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