Examkin

Question

Difficulty: HardEnhancing Reliability and Disaster Recovery

An enterprise operates a legacy web application in a single AWS account. The application's compute tier consists of Amazon ECS tasks running on AWS Fargate across three Availability Zones in the us-east-1 Region. Outbound API requests from the ECS tasks are routed to the internet through a single NAT Gateway located in a public subnet in Availability Zone us-east-1a. The data tier is hosted on a single-region Amazon Aurora MySQL DB cluster.

Recently, an outage in us-east-1a rendered the NAT Gateway unavailable, which disrupted outbound connections for ECS tasks in all three Availability Zones. To prevent future outages and enhance disaster recovery (DR) capabilities, the solutions architect must modify the architecture to achieve a recovery time objective (RTO) of 15 minutes and a recovery point objective (RPO) of 5 minutes in a secondary region (us-west-2).

Which of the following actions should the solutions architect take to meet these requirements? (Select TWO.)

  1. Deploy a NAT Gateway in a public subnet in each Availability Zone in us-east-1, and configure the route tables of the private subnets in each Availability Zone to route outbound traffic through their respective local NAT Gateway.Answer
  2. Convert the Aurora database cluster to an Aurora Global Database with a secondary cluster in us-west-2. Configure Amazon Route 53 failover routing with health checks associated with the primary Application Load Balancer to redirect traffic to the secondary region during an outage.Answer
  3. C
    Configure an AWS Lambda function triggered by Amazon CloudWatch Alarms to automatically update the private subnet route tables to point to an alternate NAT Gateway in another Availability Zone if the primary NAT Gateway fails.
  4. D
    Configure Amazon Route 53 active-passive failover routing records without health checks, relying on Route 53 to detect the Application Load Balancer's target group health status and automatically initiate DNS failover.
  5. E
    Set up nightly AWS Backup plans to copy database snapshots and S3 backups to us-west-2, and create a cross-region AWS CloudFormation template to restore the Aurora database from the copied snapshot during a failover event.

Answer

Deploy a NAT Gateway in each Availability Zone in us-east-1 with local routing, and convert the Aurora cluster to an Aurora Global Database with a secondary cluster in us-west-2 while configuring Route 53 failover routing with health checks.
Deploying a NAT Gateway in each Availability Zone ensures that the failure of a single Availability Zone does not impact outbound traffic for tasks running in other zones, establishing high availability. Converting the Aurora database to an Aurora Global Database meets the RPO of 5 minutes by continuously replicating data to us-west-2 with latency of less than one second. Configuring Route 53 DNS failover with health checks allows automatic detection of primary region degradation and redirects client traffic to the secondary region within the 15-minute RTO.

Step-by-Step Solution

1
Address the outbound connectivity single point of failure by replacing the single NAT Gateway architecture with a multi-AZ NAT Gateway setup, allocating one NAT Gateway per public subnet in each Availability Zone.
Outbound traffic from private subnets is restricted to the local NAT Gateway in the same Availability Zone, mitigating the risk of cross-AZ network failures.
This aligns with AWS best practices for high availability and ensures that the failure of a single Availability Zone only impacts Fargate tasks within that specific zone.
2
Evaluate and implement a cross-region database replication strategy that supports the recovery point objective (RPO) of 5 minutes.
Converting the single-region Aurora MySQL cluster to an Aurora Global Database with a secondary cluster in us-west-2 provides physical storage-level replication.
Aurora Global Database replication occurs with sub-second latency, meeting the 5-minute RPO constraint under failover scenarios.
3
Configure the global DNS routing policy using Route 53 active-passive failover records referencing the primary and secondary Application Load Balancers.
Associating health checks with the primary record allows Route 53 to dynamically monitor the health of the primary region's endpoint.
This configuration automates DNS failover to redirect user traffic to the secondary region within the 15-minute RTO during an outage.

Key Concept

Enhancing reliability and disaster recovery through redundant NAT Gateway architectures and active-passive multi-region database replication with DNS failover.
Rate this question

Topics

Enhancing Reliability and Disaster Recovery