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Difficulty: MediumRoute 53 DNS Failover

An organization is transitioning an internal business API from an on-premises datacenter to AWS. During the migration phase, they want to establish an active-passive failover DNS strategy using Amazon Route 53 at the zone apex. The primary gateway is hosted on-premises and is accessible via a static public IP address. The secondary disaster recovery gateway is hosted behind an Application Load Balancer (ALB) in AWS. If the on-premises endpoint becomes unavailable, traffic must automatically route to the AWS ALB.

Which two DNS record configurations should a SysOps administrator implement to meet these requirements? (Select two.)

  1. Create a Route 53 health check that monitors the on-premises public IP address, and associate this health check with a primary Failover A record pointing to the on-premises IP.Answer
  2. Create a secondary Failover Alias A record pointing to the Application Load Balancer, and configure Evaluate Target Health to Yes.Answer
  3. C
    Create a primary Failover CNAME record at the zone apex pointing to the on-premises public IP, and associate it with the created Route 53 health check.
  4. D
    Create a primary Failover A record pointing to an Amazon RDS Read Replica IP address to enable Multi-AZ automatic failover redirection.
  5. E
    Configure a CloudWatch metric alarm with standard 55-minute monitoring to track endpoint availability, and link this alarm directly to the primary record without a Route 53 health check.

Answer

Create a Route 53 health check to monitor the on-premises public IP and associate it with a primary Failover A record, and create a secondary Failover Alias A record pointing to the Application Load Balancer with Evaluate Target Health set to Yes.
To set up active-passive failover at the zone apex, the primary record must be a standard A record (since CNAMEs are not allowed at the zone apex) with a Failover routing policy and an associated health check to monitor the on-premises endpoint. The secondary record should be an Alias A record pointing to the Application Load Balancer, configured with a Failover routing policy and 'Evaluate Target Health' enabled so that Route 53 automatically tracks the health of the backend targets behind the ALB.

Step-by-Step Solution

1
Configure a Route 53 health check for the on-premises public IP address.
A health check is established that regularly pings the on-premises gateway to determine its availability.
Route 53 cannot natively check the health of non-AWS endpoints without an explicit Route 53 health check.
2
Configure the primary DNS record at the zone apex pointing to the on-premises gateway.
An A record is created at the zone apex with a Failover routing policy, marked as Primary, and associated with the health check created in Step 1.
Zone apex records cannot be CNAMEs due to DNS standards, so a standard A record with failover configuration is used.
3
Configure the secondary DNS record pointing to the AWS Application Load Balancer.
An Alias A record is created at the zone apex with a Failover routing policy, marked as Secondary, with Evaluate Target Health set to Yes.
Setting Evaluate Target Health to Yes allows Route 53 to use the health checks of the ALB's target group, eliminating the need to create a separate Route 53 health check for the secondary endpoint.

Key Concept

Route 53 active-passive DNS failover configuration for hybrid environments
Estimated Time:2m 0s
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Topics

Route 53 DNS Failover

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