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Difficulty: HardHigh Availability and Disaster Recovery Design

A global retail company is deploying a mission-critical order processing application on AWS. The primary site is located in the `us-west-2` Region, and the secondary disaster recovery (DR) site is in the `us-east-1` Region. The architecture must satisfy a Recovery Point Objective (RPO) of less than 11 minute and a Recovery Time Objective (RTO) of less than 1515 minutes. The database tier runs on Amazon Aurora PostgreSQL. Additionally, application servers in private subnets must send transaction confirmations to an external payment processor via the internet; this outbound traffic must remain highly available even during an Availability Zone (AZ) outage. Internal microservices communicate privately using a Route 53 Private Hosted Zone (PHZ). Which combination of actions will meet the disaster recovery objectives while ensuring high availability for all system components? (Select TWO.)

  1. Configure Amazon Aurora Global Database with the primary cluster in `us-west-2` and a secondary cluster in `us-east-1` to maintain an RPO of less than 11 minute. Set up Route 53 public Active-Passive Failover routing records with health checks pointing to the Application Load Balancers in both Regions to automate public DNS failover.Answer
  2. Deploy a NAT Gateway in each Availability Zone of the VPCs in both `us-west-2` and `us-east-1` to ensure highly available outbound connectivity. Associate the Route 53 Private Hosted Zone for the internal microservices with the VPCs in both Regions to ensure private DNS resolution remains operational after failover.Answer
  3. C
    Deploy a single NAT Gateway in the primary Availability Zone of each Region's VPC to route outbound traffic, and configure the subnet route tables across all Availability Zones in each VPC to point to that single NAT Gateway.
  4. D
    Set up an AWS Backup plan to perform daily snapshots of the database in `us-west-2` and replicate them to `us-east-1`. Use Route 53 Latency-based routing to automatically distribute client traffic to the region with the lowest latency.
  5. E
    Create a VPC Peering connection between the `us-west-2` and `us-east-1` VPCs, and rely on peered DNS resolution to resolve internal microservices in the Private Hosted Zone without explicitly associating the zone with the VPC in `us-east-1`.

Answer

The correct actions are to configure Amazon Aurora Global Database with Route 53 Active-Passive Failover, and to deploy redundant NAT Gateways across all Availability Zones in both regions while associating the Route 53 Private Hosted Zone with the VPCs in both regions.
Configuring Amazon Aurora Global Database provides sub-second replication lag across regions, satisfying the sub-minute RPO. Route 53 public failover routing with health checks automates traffic redirection to the secondary region within the RTO target. Additionally, deploying a NAT Gateway in each AZ avoids a single point of failure for outbound traffic, while associating the Route 53 Private Hosted Zone with the VPCs of both Regions ensures that internal name resolution works correctly in both environments.

Step-by-Step Solution

1
Select a database replication mechanism that supports an RPO of less than 11 minute across regions.
Identify that Amazon Aurora Global Database provides sub-second replication, which easily meets the RPO constraint.
Traditional backup/restore and snapshot replication methods take hours, violating the strict RPO.
2
Establish an automated multi-region DNS failover strategy that fits within the 1515-minute RTO.
Configure Route 53 Failover routing policies coupled with active health checks pointing to regional ALBs.
This automatically detects primary region failures and updates DNS records to route traffic to the secondary region within minutes.
3
Ensure outbound connectivity for payment gateway processing is highly available and resilient to AZ failures.
Deploy a NAT Gateway in each Availability Zone of the VPCs in both the primary and secondary regions.
A single NAT Gateway per region is a single point of failure; multi-AZ NAT Gateways prevent outages if one AZ goes down.
4
Configure internal service discovery for cross-region disaster recovery.
Associate the Route 53 Private Hosted Zone with the VPCs in both regions.
Route 53 Private Hosted Zones do not resolve DNS queries from another VPC unless they are explicitly associated with that VPC, even over a peered connection.

Key Concept

Multi-Region High Availability and Disaster Recovery Design
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Topics

High Availability and Disaster Recovery Design

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