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Difficulty: HardEnhancing Reliability and Disaster Recovery

An enterprise operates a transaction processing application in `us-east-1` within AWS Account A. The database tier uses an Amazon Aurora PostgreSQL cluster. To improve disaster recovery and satisfy regulatory compliance, the enterprise plans to deploy a warm standby recovery environment in `us-west-2` within AWS Account B. The target Recovery Point Objective (RPO) is 11 minute, and the Recovery Time Objective (RTO) is 1515 minutes.

The application uses an internal Route 53 Private Hosted Zone named `internal.corp` in Account A for database endpoint resolution. Additionally, during a failover event, application servers in Account B must be able to securely connect to a public third-party credit verification service via the internet.

Which of the following combinations of actions should the Solutions Architect take to enhance reliability and meet the DR requirements? (Select TWO.)

  1. Configure an Amazon Aurora Global Database with the primary cluster in `us-east-1` (Account A) and a secondary cluster in `us-west-2` (Account B). In Account A, authorize the association of the Route 53 Private Hosted Zone `internal.corp` with the VPC in Account B. In Account B, associate the VPC with the hosted zone.Answer
  2. In Account B's VPC, deploy a NAT Gateway in each public subnet across multiple Availability Zones. Configure the route table of each private subnet to route outbound traffic (0.0.0.0/00.0.0.0/0) to the NAT Gateway in the corresponding Availability Zone.Answer
  3. C
    Share the Aurora cluster in Account A with Account B using AWS Resource Access Manager (RAM) to create a cross-region Read Replica. In Account B, configure a Route 53 Resolver forwarding rule pointing to Account A's inbound resolver endpoint to resolve the `internal.corp` domain.
  4. D
    Deploy a single NAT Gateway in a public subnet in Account B's VPC, and update the route tables of all private subnets to point outbound traffic to it. Create Route 53 failover records pointing to the primary and secondary databases, omitting Route 53 health checks to speed up failover times.
  5. E
    Attach a Service Control Policy (SCP) to the Organizational Unit (OU) containing Account B to grant access to Route 53 resources in Account A. Deploy a single NAT instance in Account B with source/destination checks enabled to route outbound internet traffic.

Answer

Configure an Amazon Aurora Global Database with cross-account Route 53 Private Hosted Zone association, and deploy redundant NAT Gateways across multiple Availability Zones in the destination VPC.
The correct architecture uses Amazon Aurora Global Database to achieve the required sub-second replication latency, meeting the 1-minute RPO constraint. To ensure that database hostnames resolve correctly in Account B, the Route 53 Private Hosted Zone from Account A must be associated with the VPC in Account B using cross-account VPC association authorization. To prevent outbound communication failures to the payment gateway in the event of an Availability Zone outage, the NAT Gateways must be redundantly deployed in each public subnet, mapping to the respective Availability Zones.

Step-by-Step Solution

1
Address database replication requirements for the RPO threshold.
Implement Aurora Global Database to achieve sub-second cross-region replication lag, meeting the target RPO of under 1 minute.
Aurora Global Database is the standard managed solution for cross-region disaster recovery with near-zero replication lag.
2
Configure DNS resolution for database endpoints across accounts.
Authorize the VPC association from the owner account (Account A) and associate it inside the destination VPC account (Account B).
This allows resources in Account B to resolve DNS queries against the Private Hosted Zone hosted in Account A without using complex resolver forwarding rules.
3
Ensure outbound connectivity in the secondary region is highly available.
Deploy a NAT Gateway in each Availability Zone in Account B's VPC.
Using a single NAT Gateway introduces a single point of failure, meaning an outage in the hosting Availability Zone would break outbound API validation queries.

Key Concept

Disaster recovery preparation requires highly resilient database replication, cross-account DNS host mapping, and redundant network egress points.
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Topics

Enhancing Reliability and Disaster Recovery