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Difficulty: MediumRoute 53 DNS Failover

A company hosts a web application on Amazon EC2 instances behind an Application Load Balancer (ALB) in the us-east-1 Region. The company wants to set up an active-passive failover configuration at the zone apex (example.com). If the ALB or the backend instances become unhealthy, Route 53 must automatically redirect traffic to a static maintenance website hosted in an Amazon S3 bucket in the us-west-2 Region. Which configuration will meet these requirements with the fastest failover response and the least configuration overhead?

  1. Create an Alias record at the zone apex using a Failover routing policy. Set the primary record to point to the ALB with Evaluate Target Health set to Yes. Set the secondary record to point to the S3 bucket website endpoint.Answer
  2. B
    Create a CNAME record at the zone apex using a Failover routing policy. Set the primary record to point to the ALB DNS name and associate a Route 53 health check. Set the secondary record to point to the S3 bucket website endpoint.
  3. C
    Create a Weighted routing policy at the zone apex. Set the primary record to point to the ALB with a weight of 100 and associate a Route 53 health check. Set the secondary record to point to the S3 bucket website endpoint with a weight of 0.
  4. D
    Create an Alias record at the zone apex using a Failover routing policy. Set the primary record to point to the ALB. Create a Route 53 health check that monitors a CloudWatch alarm based on standard 5-minute ALB metrics, and associate it with the primary record. Set the secondary record to point to the S3 bucket website endpoint.

Answer

Create an Alias record at the zone apex using a Failover routing policy, pointing the primary record to the Application Load Balancer with Evaluate Target Health enabled, and pointing the secondary record to the Amazon S3 bucket website endpoint.
The correct option is the configuration that creates an Alias record at the zone apex using a Failover routing policy, points the primary record to the Application Load Balancer (ALB) with 'Evaluate Target Health' enabled, and points the secondary record to the Amazon S3 bucket website endpoint. This setup is standard, complies with zone apex limitations by using an Alias record instead of a CNAME, and provides rapid failover by having Route 53 directly evaluate the ALB target health without needing a separate health check or a delayed CloudWatch alarm.

Step-by-Step Solution

1
Select the zone apex record (example.com) and set the routing policy to Failover.
Allows creation of primary and secondary records for active-passive failover.
Failover routing is the standard policy for active-passive disaster recovery setups.
2
Configure the primary record as an Alias record pointing to the Application Load Balancer, and set 'Evaluate Target Health' to Yes.
Route 53 will automatically check the health of the ALB and its targets without requiring a manual Route 53 health check setup.
Alias records to ALBs can leverage 'Evaluate Target Health' to quickly detect ALB target group health changes.
3
Configure the secondary record as an Alias record pointing to the S3 bucket website endpoint.
Traffic will failover to the S3 static website when the ALB is determined to be unhealthy.
Provides a cost-effective and highly available passive backup endpoint.

Key Concept

Route 53 active-passive DNS failover using Alias records and target health evaluation.
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Topics

Route 53 DNS Failover

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