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Difficulty: MediumRoute 53 DNS Failover

A company hosts a web application behind an Application Load Balancer (ALB) in the us-west-2 Region. The company uses Amazon Route 53 with active-passive failover routing to redirect traffic to a backup static website in Amazon S3 if the primary application goes down. The SysOps Administrator configures a Route 53 health check to monitor a CloudWatch alarm. The alarm is based on the UnHealthyHostCount metric for the ALB's target group in us-west-2. During an application outage where all backend instances become unresponsive and stop reporting metrics, the Route 53 health check status remains 'Healthy' and failover does not occur. Which of the following configuration changes are required to resolve this issue? (Select TWO.)

  1. Recreate the CloudWatch alarm in the us-east-1 Region, referencing the ALB metrics from the us-west-2 Region.Answer
  2. Configure the Route 53 health check to treat insufficient data (INSUFFICIENT_DATA state) as unhealthy.Answer
  3. C
    Change the routing policy of the primary Route 53 record from Failover to Weighted, and set the weight of the primary record to 0.
  4. D
    Enable detailed monitoring on the ALB target group to increase the metric resolution to 1 minute, which automatically resolves the INSUFFICIENT_DATA status.
  5. E
    Configure the S3 bucket to act as an RDS Multi-AZ standby replica to allow synchronous database-level replication and DNS redirection.

Answer

Recreating the CloudWatch alarm in the us-east-1 Region (referencing the us-west-2 ALB metrics) and configuring the Route 53 health check to treat insufficient data (INSUFFICIENT_DATA state) as unhealthy.
The correct configurations involve recreating the CloudWatch alarm in us-east-1 because Route 53 health checks can only monitor alarms in that specific Region, and configuring the health check to treat the INSUFFICIENT_DATA state as unhealthy to trigger failover when metrics stop reporting.

Step-by-Step Solution

1
Identify the regional requirements for Route 53 health checks monitoring CloudWatch alarms.
Confirm that Route 53 can only integrate with CloudWatch alarms created in the us-east-1 Region, regardless of the target resource's Region.
Route 53's integration with CloudWatch is globally anchored in the N. Virginia Region.
2
Analyze the behavior of the CloudWatch alarm when metrics are missing.
Recognize that when all backend instances go down and stop reporting metrics, the alarm status changes to INSUFFICIENT_DATA.
Without active reporting from targets, no metric values are sent, resulting in missing data points.
3
Adjust the health check state configuration for missing data.
Configure the Route 53 health check to treat the INSUFFICIENT_DATA state as unhealthy so that the primary record is marked unhealthy and traffic fails over.
By default, Route 53 may not treat insufficient data as a failure state, which prevents failover.

Key Concept

Route 53 DNS Failover using CloudWatch Alarms
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Topics

Route 53 DNS Failover

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