A financial services firm hosts a critical transactional application on AWS. The applicati… — AWS Certified Solutions Architect - Professional

A financial services firm hosts a critical transactional application on AWS. The application runs on Amazon ECS tasks on AWS Fargate in the us-east-1 Region, across three Availability Zones. The tasks connect to an Amazon Aurora MySQL database cluster in the same Region. Outbound traffic to external payment processors is routed through a single NAT Gateway located in one of the public subnets.

The firm needs to enhance the reliability of the system and establish a disaster recovery (DR) strategy in the us-west-2 Region. The DR solution must support a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 5 minutes. Additionally, the outbound connectivity in the primary Region must be highly resilient against Availability Zone failures.

Which TWO actions should the Solutions Architect take to meet these requirements?

Configure Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Pre-deploy the Amazon ECS tasks on AWS Fargate in us-west-2 at a minimum scale, and set up Amazon Route 53 Application Recovery Controller (ARC) routing controls to manage failover.Answer
Deploy a NAT Gateway in each Availability Zone within the primary Region, and update the private subnet route tables to route outbound internet traffic through the NAT Gateway in their respective Availability Zone.Answer
C
Set up a cross-Region Aurora replica in the secondary Region, and schedule daily database backups. Upon failover, restore the database from the backup to achieve the lowest cost solution.
D
Implement a Route 53 active-passive failover routing policy pointing to Application Load Balancers in both Regions, disabling Route 53 health checks on the primary record to prevent false failover triggers.
E
Maintain the single NAT Gateway configuration in the primary Region, and configure all private subnet route tables to use this gateway to simplify network architecture and reduce costs.
F
Deploy a Route 53 Private Hosted Zone for database endpoint resolution, but do not associate it with the standby VPC in us-west-2 to avoid cross-VPC DNS resolution overhead.

Answer

The correct options are deploying a NAT Gateway in each Availability Zone within the primary Region to remove the single point of failure, and configuring an Amazon Aurora Global Database with pre-deployed ECS tasks on Fargate at a minimum scale in the secondary Region managed by Route 53 ARC to meet the RTO/RPO targets.

Deploying a NAT Gateway per Availability Zone removes the single point of failure in the primary Region's outbound traffic. Implementing Amazon Aurora Global Database alongside pre-deployed ECS tasks in the secondary Region ensures RPO is under 1 second and RTO is under 15 minutes, with Route 53 ARC providing controlled and fast failover orchestration.

Step-by-Step Solution

Address the single point of failure in the outbound path within the primary Region.

Identify that the single NAT Gateway in us-east-1 is a bottleneck and risk. To achieve resiliency against Availability Zone failures, deploy a NAT Gateway in each Availability Zone and associate them with the respective private subnet route tables.

This isolates Availability Zone failures and ensures outbound internet traffic continues flowing from the remaining healthy zones.

Select a database disaster recovery pattern that meets the 5-minute RPO.

Choose Amazon Aurora Global Database, which replicates data asynchronously to the secondary Region with typical lag of less than 1 second.

This comfortably satisfies the RPO requirement of 5 minutes without the data loss associated with daily backups.

Select a compute disaster recovery pattern that meets the 15-minute RTO.

Pre-deploy the ECS Fargate tasks at a minimum scale in the secondary Region and use Route 53 ARC for rapid failover routing.

Pre-deploying the ECS tasks allows the compute layer to scale out rapidly rather than starting from scratch, fitting the tight 15-minute RTO.

Key Concept

Enhancing existing infrastructure reliability requires eliminating single points of failure (such as single NAT Gateways) and using multi-region database replication (like Aurora Global Database) combined with warm standby compute patterns to meet low RTO and RPO objectives.

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