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Zorluk: ZorRoute 53 Routing Policies and DNS Failover Strategies

A company hosts a stateful transaction processing 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 disaster recovery (DR) configuration using a secondary scaled-down environment behind an ALB in the eu-west-1 Region. The DR plan requires automatic failover to the secondary region if the primary region's application or its underlying database becomes unavailable. To avoid database write conflicts, the application in the secondary region must not receive traffic unless a failover is active. Which two configurations should a solutions architect implement to meet these requirements? (Select two.)

  1. Configure Route 53 Failover routing alias records pointing to the ALB in each region, and set the Evaluate Target Health option to Yes on both records.Cevap
  2. Configure the primary Application Load Balancer (ALB) target group health check to query a deep path (such as /health) that verifies database connectivity, so targets are marked unhealthy if the database is offline.Cevap
  3. C
    Configure Route 53 Latency routing records pointing to both the primary and secondary ALBs to automatically route traffic based on network latency, and rely on Route 53 to fail over to the standby region if the primary region goes offline.
  4. D
    Create standard CNAME records pointing to the primary and secondary ALB DNS names, and enable the Evaluate Target Health option on both records to allow Route 53 to monitor the load balancer health.
  5. E
    Configure Route 53 Failover routing policies to route database traffic directly to the RDS Read Replica in the secondary region by using Route 53 DNS records to handle automatic read-replica promotion and database write failover.

Cevap

The correct configurations are to set up Route 53 Failover routing alias records with Evaluate Target Health enabled, and to implement a deep health check endpoint on the primary Application Load Balancer target group to verify database availability.
To implement a resilient active-passive configuration, the solutions architect should use Route 53 Failover routing records. These records must be configured as Alias records pointing to the respective Application Load Balancers (ALBs) to support the Evaluate Target Health feature. Additionally, because the database status dictates the availability of this stateful application, a deep health check endpoint (like /health) must be configured on the primary ALB's target group. This ensures that a database failure marks the targets and the load balancer as unhealthy, prompting Route 53 to trigger failover.

Adım Adım Çözüm

1
Determine the routing policy that meets the active-passive constraint.
Route 53 Failover routing policy is the correct choice, as it ensures traffic is directed to the primary region and only switches to the secondary region if the primary becomes unhealthy. Policies like Latency routing are active-active and do not satisfy this requirement.
Active-passive routing is required to prevent write conflicts on a stateful database.
2
Select the correct DNS record type to enable Route 53 health monitoring of AWS resources.
Route 53 Alias records must be used because they natively support the 'Evaluate Target Health' option, which queries the ALB health. Standard CNAME records do not support this feature.
Ensuring the correct record type is used is critical for integrating DNS routing with resource health status.
3
Determine how Route 53 will detect database-level failures.
Configure the ALB target group health check to hit a '/health' endpoint that runs a query against the database. When the database is offline, the EC2 targets fail the check, the ALB becomes unhealthy, and Route 53 detects this via the Evaluate Target Health setting.
Standard ALB target group checks only verify if the web server is listening, which would miss database outages.

Anahtar Kavram

Route 53 active-passive failover requires Failover routing alias records combined with deep application health checks on the load balancer's targets.
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Route 53 Routing Policies and DNS Failover Strategies

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