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Difficulty: HardHigh Availability and Disaster Recovery Design

A geospatial satellite image processing company is designing a new multi-region pipeline on AWS. The application will be deployed in VPCs in us-east-1 (Primary) and us-west-2 (Secondary). The workflow orchestration tier runs on Amazon EC2 instances in private subnets that require highly available outbound internet access to ingestion APIs, resilient to any Availability Zone (AZ) failure. The database layer uses Amazon Aurora PostgreSQL to store image metadata. The company requires a Recovery Point Objective (RPO) of less than 1 minute and a Recovery Time Objective (RTO) of less than 2 minutes. Additionally, internal EC2 processing nodes in us-west-2 must resolve hostnames in a Route 53 Private Hosted Zone (PHZ) managed in us-east-1. Which TWO architectural configurations must a solutions architect implement to satisfy these requirements? (Select TWO.)

  1. Configure an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Use managed failover to promote the secondary cluster to a write-capable region during disaster recovery.Answer
  2. In both VPCs, deploy a NAT Gateway in each Availability Zone where private EC2 instances reside, and configure the routing tables of each private subnet to direct egress traffic to the local NAT Gateway in its respective Availability Zone.Answer
  3. C
    Use AWS Backup to schedule database snapshots every 12 hours in us-east-1 and copy them to us-west-2 to restore the database in the event of an outage.
  4. D
    Deploy a single NAT Gateway in the primary Availability Zone of each VPC, and configure the routing tables of all private subnets in that VPC to route egress traffic through this NAT Gateway.
  5. E
    Rely on standard VPC Peering DNS resolution settings to allow the instances in us-west-2 to resolve hostnames in the primary VPC's Route 53 Private Hosted Zone without modifying the zone's VPC associations.
  6. F
    Configure Amazon Aurora Auto Scaling in us-west-2 to automatically scale the number of writer nodes to handle database failover and host resolution during a regional outage.

Answer

The correct configurations are to configure an Amazon Aurora Global Database using managed failover, and to deploy NAT Gateways in multiple Availability Zones in each VPC with updated route tables for each private subnet.
Configuring an Amazon Aurora Global Database satisfies the low RTO and RPO limits. Aurora Global Database utilizes fast storage-level replication to achieve an RPO of under 1 second, and its managed failover enables promoting the secondary region to primary within 2 minutes. Additionally, deploying a NAT Gateway in each Availability Zone where private EC2 instances reside ensures outbound internet connection remains available in the event of an Availability Zone outage, since each zone's private route tables route egress traffic independently to the local NAT Gateway.

Step-by-Step Solution

1
Evaluate the HA/DR requirements for the database tier to determine the replication mechanism.
Identify that a backup/restore or snapshot replication mechanism cannot meet the 1-minute RPO and 2-minute RTO. Amazon Aurora Global Database replication latency is under 1 second, and its managed failover meets the under 2 minutes RTO requirement.
This establishes the database replication and failover architecture needed for compliance with recovery objectives.
2
Evaluate the egress internet traffic resilience requirements.
Identify that a single NAT Gateway in a VPC is a single point of failure. Deploying a NAT Gateway in each Availability Zone where EC2 instances reside and updating corresponding route tables maintains internet access if one AZ goes down.
This ensures the outbound connection path remains highly available and AZ-fault tolerant.
3
Review options to eliminate distractors violating RTO/RPO, AZ resilience, DNS Private Hosted Zone cross-VPC association, or database replica scaling constraints.
Select the correct combination consisting of Aurora Global Database with managed failover, and multi-AZ NAT Gateway deployments.
This guarantees that both database and networking layers fulfill all business constraints.

Key Concept

Designing multi-region disaster recovery for databases and highly available network paths while managing private DNS resolution across VPCs.
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Topics

High Availability and Disaster Recovery Design

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