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Difficulty: MediumRoute 53 Routing Policies and DNS Failover Strategies

A healthcare technology company hosts its patient check-in portal at the apex domain patientcheck.com. The primary environment runs on Amazon EC2 instances behind an Application Load Balancer (ALB) in the us-east-1 Region. The company wants to implement an active-passive disaster recovery strategy. If the primary environment in us-east-1 experiences an outage, Route 53 must automatically redirect all incoming client traffic to a standby static maintenance website hosted in an Amazon S3 bucket in the us-west-2 Region. Which combination of Route 53 configurations will meet these requirements?

  1. A
    Configure a primary Failover CNAME record for patientcheck.com pointing to the Application Load Balancer DNS name, and configure a secondary Failover CNAME record pointing to the Amazon S3 bucket website endpoint.
  2. B
    Configure a primary Latency Alias record for patientcheck.com pointing to the Application Load Balancer with Evaluate Target Health set to Yes, and configure a secondary Latency Alias record pointing to the Amazon S3 bucket website endpoint.
  3. Configure a primary Failover Alias record for patientcheck.com pointing to the Application Load Balancer with Evaluate Target Health set to Yes, and configure a secondary Failover Alias record pointing to the Amazon S3 bucket website endpoint.Answer
  4. D
    Configure a primary Failover Alias record for patientcheck.com pointing to the Application Load Balancer with Evaluate Target Health set to No, and create a Route 53 HTTP health check to monitor the Amazon S3 bucket website endpoint.

Answer

Configure a primary Failover Alias record for patientcheck.com pointing to the Application Load Balancer with Evaluate Target Health set to Yes, and configure a secondary Failover Alias record pointing to the Amazon S3 bucket website endpoint.
The correct configuration uses a primary Failover Alias record pointing to the Application Load Balancer with Evaluate Target Health set to Yes, and a secondary Failover Alias record pointing to the Amazon S3 bucket website endpoint. Route 53 Alias records allow the zone apex to point directly to AWS resources without violating DNS standards. Enabling Evaluate Target Health ensures Route 53 monitors the health of the Application Load Balancer using the health of its targets, automatically failing over to the secondary S3 bucket when the load balancer becomes unhealthy.

Step-by-Step Solution

1
Identify the DNS limitations for the zone apex domain (patientcheck.com).
Determine that CNAME records cannot be created for the zone apex, requiring the use of Route 53 Alias records instead.
Standard DNS specifications do not allow CNAME records at the zone apex, but Route 53 Alias records can map the zone apex directly to AWS resources.
2
Select the appropriate routing policy for the active-passive disaster recovery strategy.
Choose the Failover routing policy with primary and secondary record types.
Failover routing directs traffic to a primary resource when it is healthy, and to a secondary resource when the primary resource is unhealthy.
3
Enable health monitoring on the primary resource.
Set Evaluate Target Health to Yes on the primary Failover Alias record pointing to the Application Load Balancer.
Evaluate Target Health allows Route 53 to use the health checks configured on the Application Load Balancer's target groups to determine if the primary endpoint is healthy.

Key Concept

Active-passive DNS failover using Route 53 Failover Alias records at the zone apex.
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Topics

Route 53 Routing Policies and DNS Failover Strategies

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