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Difficulty: MediumRoute 53 Routing Policies and DNS Failover Strategies

A company hosts its core transactional platform on Amazon EC2 instances behind an Application Load Balancer (ALB) in us-east-1 as the primary region. The company maintains a fully functional but scaled-down warm standby environment behind an ALB in us-west-2 as the secondary region. The database layer is replicated across both regions. A solutions architect must design a DNS routing strategy using Amazon Route 53 to automatically redirect user traffic from the primary region to the secondary region if the primary region's ALB or backend instances fail. Which configuration should the solutions architect implement to meet these requirements?

  1. Create Route 53 Failover Alias records for the application's domain. Point the primary record to the us-east-1 ALB and the secondary record to the us-west-2 ALB, with 'Evaluate Target Health' set to Yes for both records.Answer
  2. B
    Create Route 53 Latency routing records pointing to the primary and secondary ALBs, relying on Route 53 to naturally steer traffic to the secondary region when the primary region's latency increases during an outage.
  3. C
    Create Route 53 Failover records where the primary record points to the us-east-1 ALB, and the secondary record points directly to the Amazon RDS Read Replica endpoint in us-west-2 to automatically promote it and accept write traffic.
  4. D
    Create Route 53 Failover records where the secondary record points to a shut-down pilot light EC2 environment, relying on the Route 53 health check failure to automatically start the EC2 instances in us-west-2 without administrative intervention.

Answer

Create Route 53 Failover Alias records for the application's domain. Point the primary record to the us-east-1 ALB and the secondary record to the us-west-2 ALB, with 'Evaluate Target Health' set to Yes for both records.
The correct configuration is to create Route 53 Failover Alias records pointing to the primary and secondary Application Load Balancers (ALBs) and to enable 'Evaluate Target Health'. Route 53 Failover routing is designed specifically for active-passive disaster recovery setups. By using Alias records and enabling 'Evaluate Target Health', Route 53 utilizes the health check configuration of the ALBs. If the primary ALB or all backend EC2 instances registered to it fail their health checks, Route 53 automatically detects this and redirects traffic to the secondary ALB in the warm standby region.

Step-by-Step Solution

1
Select Route 53 Failover routing policy for the domain's record set.
Defines an active-passive configuration where traffic is directed to the primary resource by default and to the secondary resource when the primary is unhealthy.
This matches the requirement to redirect traffic to the warm standby in us-west-2 only if the primary us-east-1 environment becomes unavailable.
2
Configure the primary Failover record as an Alias record pointing to the primary ALB, and the secondary Failover record as an Alias record pointing to the secondary ALB.
Allows Route 53 to map the domain name directly to the AWS ALB DNS names without incurring CNAME lookup costs or delays.
Alias records are the recommended way to integrate Route 53 with AWS load balancers.
3
Enable 'Evaluate Target Health' on both the primary and secondary Alias records.
Route 53 actively monitors the health of the underlying ALB target groups using the load balancer's configured health checks.
If target health evaluation is disabled, Route 53 will continue to route traffic to the primary ALB even if all backend instances behind it are unhealthy.

Key Concept

Route 53 Routing Policies and DNS Failover Strategies
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Topics

Route 53 Routing Policies and DNS Failover Strategies

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