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Difficulty: MediumHigh Availability and Disaster Recovery Design

A municipal utility provider is deploying a new smart-meter data collection platform. The architecture resides in two AWS Regions, using us-east-1 as primary and us-west-2 as secondary. The backend database requires a Recovery Point Objective (RPO) of 1 minute and a Recovery Time Objective (RTO) of 15 minutes. The web application tier runs on Amazon EC2 instances in private subnets, which require continuous egress to public external APIs for device validation. Which multi-region configuration meets these requirements while minimizing operational complexity and cost?

  1. Deploy Amazon Aurora Global Database with the primary writer in us-east-1 and a read replica in us-west-2. Deploy redundant NAT Gateways across multiple Availability Zones in each Region's VPC. Use Route 53 Failover routing policies with active health checks to manage DNS failover.Answer
  2. B
    Deploy Amazon Aurora Global Database with the primary writer in us-east-1 and a read replica in us-west-2. Deploy a single NAT Gateway in each Region to route egress traffic from all private subnets. Use Route 53 Failover routing policies with active health checks to manage DNS failover.
  3. C
    Deploy a single-region Amazon Aurora cluster in us-east-1 and configure hourly AWS Backup copies to us-west-2. Deploy redundant NAT Gateways across multiple Availability Zones in each Region's VPC. Configure Route 53 Failover routing policies to redirect traffic to us-west-2 where the database will be restored from backup during an outage.
  4. D
    Deploy Amazon Aurora Global Database with the primary writer in us-east-1 and a read replica in us-west-2. Deploy redundant NAT Gateways across multiple Availability Zones in each Region's VPC. Use Route 53 Failover routing policies without health checks, relying on manual DNS record modifications during a disaster event.

Answer

Deploy Amazon Aurora Global Database with the primary writer in us-east-1 and a read replica in us-west-2. Deploy redundant NAT Gateways across multiple Availability Zones in each Region's VPC. Use Route 53 Failover routing policies with active health checks to manage DNS failover.
The correct solution combines Amazon Aurora Global Database to achieve low-latency replication (meeting the 1-minute RPO) and fast failover (meeting the 15-minute RTO), redundant NAT Gateways across Availability Zones to avoid a single point of failure for outbound internet traffic, and Route 53 Failover routing policies with active health checks to automate the redirection of user traffic.

Step-by-Step Solution

1
Select the database replication strategy based on RPO and RTO.
Amazon Aurora Global Database provides millisecond-level replication lag to the secondary region and supports rapid promotion of the secondary cluster (typically under 1 minute), which satisfies both the 1-minute RPO and 15-minute RTO.
Traditional backup-and-restore or standard cross-region snapshot copy methods cannot meet the 1-minute RPO or the 15-minute RTO.
2
Ensure outbound connectivity redundancy for the application tier in private subnets.
Redundant NAT Gateways must be deployed in each Availability Zone in both regions.
A single NAT Gateway per VPC is a single point of failure; if the Availability Zone containing the NAT Gateway fails, resource connectivity to external APIs from other Availability Zones is lost.
3
Configure DNS routing and automated failover mechanics.
Use Route 53 Failover routing policies configured with health checks pointing to the application endpoints.
Active health checks allow Route 53 to automatically detect a regional outage and reroute traffic without manual intervention, helping to ensure the 15-minute RTO is met.

Key Concept

Disaster Recovery pattern selection combined with multi-AZ network redundancy and DNS routing failover configurations.
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Topics

High Availability and Disaster Recovery Design

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