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Difficulty: MediumAmazon Route 53 DNS Configuration and Routing Policies

An organization runs a web application on four Amazon EC2 instances, each configured with an Elastic IP address. A SysOps Administrator must configure Amazon Route 53 to distribute client requests randomly across all four instances. The configuration must perform health checks on each instance individually and automatically stop routing traffic to any instance that becomes unhealthy. Which Route 53 configuration will meet these requirements?

  1. A
    Create a single A record using the Simple routing policy that contains all four Elastic IP addresses, and enable health checking on the record.
  2. Create four A records using the Multivalue Answer routing policy, and associate a Route 53 health check with each record.Answer
  3. C
    Create a CNAME record at the zone apex pointing to a Route 53 traffic policy that distributes traffic across the four Elastic IP addresses.
  4. D
    Create four Alias records pointing to the Elastic IP addresses using the Failover routing policy, and associate health checks.

Answer

Create four A records using the Multivalue Answer routing policy, and associate a Route 53 health check with each record.
The correct option is to create four A records using the Multivalue Answer routing policy and associate a Route 53 health check with each record. This configuration returns multiple healthy values (up to eight) in response to DNS queries, allows Route 53 to check the health of each resource individually, and automatically excludes unhealthy resources from DNS responses. It also allows direct access to each IP address for individual health checking.

Step-by-Step Solution

1
Determine the resource type and record type requirements.
Since the targets are individual EC2 Elastic IP addresses, standard A records must be used (not Alias records, which require AWS resources like load balancers).
Alias records do not support target IP addresses directly.
2
Select a routing policy that supports individual health checks for multiple distinct records.
Choose Multivalue Answer routing rather than Simple routing.
Multivalue Answer routing allows associating a health check with each individual A record, whereas Simple routing applies health checks to the record as a whole and cannot selectively remove individual IPs.
3
Associate a health check with each of the four A records.
Configure Route 53 health checks to monitor each EC2 instance's IP address.
When a health check fails, Route 53 stops returning the corresponding IP address in DNS query responses.

Key Concept

Amazon Route 53 Multivalue Answer routing policy with health checks for active-active DNS load balancing and failover.
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Amazon Route 53 DNS Configuration and Routing Policies

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