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Difficulty: HardEnhancing Reliability and Disaster Recovery

A logistics company operates a fleet tracking application across multiple AWS accounts within an AWS Organization. The primary application tier runs in the `us-west-2` region under Account A (Production), and an active-passive disaster recovery (DR) environment is established in `us-east-1` under Account B (Disaster Recovery). The database layer uses Amazon Aurora PostgreSQL. The application servers, hosted on Amazon EC2 instances in private subnets across 33 Availability Zones, depend on an internal API gateway deployed in a shared services VPC in Account C (Shared Services). This internal dependency is resolved privately using a Route 5353 Private Hosted Zone (PHZ) hosted in Account C.

During a disaster recovery simulation, the following issues were documented:
1. Outbound telemetry data transmission to external APIs failed when a single Availability Zone (AZ) in `us-west-2` experienced an outage, because all private subnets were routing internet-bound traffic through a single NAT Gateway located in that AZ.
2. When the primary database was manually stopped to simulate a regional failure, client traffic was not redirected to `us-east-1` because the Route 5353 failover routing policy was monitoring the Application Load Balancer (ALB) health, which remained healthy as the web servers were still running and returning a 200200 OK status.
3. After database failover to `us-east-1` was forced, the application servers in Account B failed to resolve the internal API gateway domain hosted in Account C.

Which set of actions will resolve these issues while meeting a target Recovery Time Objective (RTO) of 1515 minutes and a Recovery Point Objective (RPO) of 11 minute?

  1. Configure Amazon Aurora Global Database with the primary cluster in `us-west-2` and a secondary cluster in `us-east-1`. Deploy a NAT Gateway in each Availability Zone of the VPCs in both Account A and Account B. Create a Route 5353 health check targeting a custom deep health check endpoint on the application that actively queries the database. Authorize the Account B VPC to associate with the Account C Private Hosted Zone by running the `create-vpc-association-authorization` command from Account C, and then associate the VPC from Account B.Answer
  2. B
    Implement a backup plan using AWS Backup to copy Aurora snapshots from Account A to Account B every 1212 hours. Deploy a single NAT Gateway in each VPC to minimize idle resource costs. Create a Route 5353 health check targeting the ALB's default DNS name. Share the Route 5353 Private Hosted Zone from Account C with Account B using AWS Resource Access Manager, then associate the VPC in Account B.
  3. C
    Configure Amazon Aurora Global Database with the primary cluster in `us-west-2` and a secondary cluster in `us-east-1`. Deploy a single NAT Gateway in a shared public subnet in each region to route all egress traffic. Set up a Route 5353 health check targeting a custom deep health check endpoint that queries the database. Establish a VPC peering connection between Account B and Account C to enable private resolution of the internal API gateway domain without associating the Private Hosted Zone.
  4. D
    Configure Amazon Aurora Global Database with the primary cluster in `us-west-2` and a secondary cluster in `us-east-1`. Deploy a NAT Gateway in each Availability Zone of both VPCs. Configure Route 5353 failover records using the ALB's default health check. Create an inbound Route 5353 Resolver endpoint in Account C and associate the Private Hosted Zone with the Account B VPC directly from the Account B AWS Management Console without cross-account authorization.

Answer

The correct option is the one that configures Amazon Aurora Global Database, deploys a NAT Gateway in each Availability Zone of the VPCs, utilizes a custom deep health check endpoint to monitor database connectivity, and establishes the cross-account Private Hosted Zone association using the Route 5353 VPC association authorization workflow.
The correct option addresses all three failure scenarios according to AWS best practices: it uses Amazon Aurora Global Database to achieve the required 11 minute RPO and 1515 minutes RTO; it secures egress high availability by placing a NAT Gateway in each Availability Zone; it monitors application health holistically with a deep health check; and it correctly follows the cross-account Private Hosted Zone association API workflow.

Step-by-Step Solution

1
Address database replication requirements.
Configure Amazon Aurora Global Database spanning `us-west-2` and `us-east-1`.
Aurora Global Database provides sub-second RPO and promotes a secondary region in under 11 minute, satisfying the target RPO of 11 minute and RTO of 1515 minutes.
2
Ensure egress connectivity reliability.
Deploy a NAT Gateway in each Availability Zone containing private subnets in both Account A and Account B.
This removes the single point of failure where an Availability Zone outage could disable internet egress for the remaining zones.
3
Configure DNS-level failover monitoring.
Create a Route 5353 health check targeting an application endpoint that performs a database query.
A shallow load balancer health check only verifies that the web/app servers are responding, failing to detect database outages. A deep health check ensures failover triggers when the database is unreachable.
4
Establish cross-account DNS resolution.
Execute `create-vpc-association-authorization` in Account C for the Account B VPC, then run `associate-vpc-with-hosted-zone` in Account B.
Private Hosted Zones must be explicitly associated with consumer VPCs across different accounts, requiring an authorization step from the zone's owner account.

Key Concept

Multi-region disaster recovery coordination involving database replication, redundant network egress paths, deep application health checks, and secure cross-account private DNS hosting.
Estimated Time:3m 0s
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Topics

Enhancing Reliability and Disaster Recovery