AliasTarget

Alias resource record sets only: The external DNS name associated with the AWS Resource. The value that you specify depends on where you want to route queries:

• A CloudFront distribution: Specify the domain name that CloudFront assigned when you created your distribution. Your CloudFront distribution must include an alternate domain name that matches the name of the resource record set. For example, if the name of the resource record set is acme.example.com, your CloudFront distribution must include acme.example.com as one of the alternate domain names. For more information, see Using Alternate Domain Names (CNAMEs) in the Amazon CloudFront Developer Guide.
• An ELB load balancer: Specify the DNS name associated with the load balancer. You can get the DNS name by using the AWS Management Console, the ELB API, or the AWS CLI. Use the same method to get values for HostedZoneId and DNSName. If you get one value from the console and the other value from the API or the CLI, creating the resource record set will fail.
• An Elastic Beanstalk environment: Specify the CNAME attribute for the environment. (The environment must have a regionalized domain name.)
• An Amazon S3 bucket that is configured as a static website: Specify the domain name of the Amazon S3 website endpoint in which you created the bucket; for example, s3-website-us-east-1.amazonaws.com. For more information about valid values, see the table Amazon Simple Storage Service (S3) Website Endpoints in the Amazon Web Services General Reference. For more information about using Amazon S3 buckets for websites, see Hosting a Static Website on Amazon S3 in the Amazon Simple Storage Service Developer Guide.
• Another Amazon Route 53 resource record set: Specify the value of the Name element for a resource record set in the current hosted zone.

For more information and an example, see Example: Creating Alias Resource Record Sets in the Amazon Route 53 API Reference.

Alias resource record sets only: If you set the value of EvaluateTargetHealth to true for the resource record set or sets in an alias, weighted alias, latency alias, or failover alias resource record set, and if you specify a value for HealthCheckId for every resource record set that is referenced by these alias resource record sets, the alias resource record sets inherit the health of the referenced resource record sets.

In this configuration, when Amazon Route 53 receives a DNS query for an alias resource record set:

1. Amazon Route 53 looks at the resource record sets that are referenced by the alias resource record sets to determine which health checks they're using.
2. Amazon Route 53 checks the current status of each health check. (Amazon Route 53 periodically checks the health of the endpoint that is specified in a health check; it doesn't perform the health check when the DNS query arrives.)
3. Based on the status of the health checks, Amazon Route 53 determines which resource record sets are healthy. Unhealthy resource record sets are immediately removed from consideration. In addition, if all of the resource record sets that are referenced by an alias resource record set are unhealthy, that alias resource record set also is immediately removed from consideration.
4. Based on the configuration of the alias resource record sets (weighted alias or latency alias, for example) and the configuration of the resource record sets that they reference, Amazon Route 53 chooses a resource record set from the healthy resource record sets, and responds to the query.

Note the following:

• You cannot set EvaluateTargetHealth to true when the alias target is a CloudFront distribution.
• If the AWS resource that you specify in AliasTarget is a resource record set or a group of resource record sets (for example, a group of weighted resource record sets), but it is not another alias resource record set, we recommend that you associate a health check with all of the resource record sets in the alias target. For more information, see What Happens When You Omit Health Checks? in the Amazon Route 53 Developer Guide.
• If you specify an ELB load balancer in AliasTarget, Elastic Load Balancing routes queries only to the healthy Amazon EC2 instances that are registered with the load balancer. If no Amazon EC2 instances are healthy or if the load balancer itself is unhealthy, and if EvaluateTargetHealth is true for the corresponding alias resource record set, Amazon Route 53 routes queries to other resources.
• When you create a load balancer, you configure settings for Elastic Load Balancing health checks; they're not Amazon Route 53 health checks, but they perform a similar function. Do not create Amazon Route 53 health checks for the Amazon EC2 instances that you register with an ELB load balancer. For more information, see How Health Checks Work in More Complex Amazon Route 53 Configurations in the Amazon Route 53 Developer Guide.

We recommend that you set EvaluateTargetHealth to true only when you have enough idle capacity to handle the failure of one or more endpoints.

For more information and examples, see Amazon Route 53 Health Checks and DNS Failover in the Amazon Route 53 Developer Guide.

Alias resource record sets only: The value you use depends on where you want to route queries:

• A CloudFront distribution: Specify Z2FDTNDATAQYW2.
• An ELB load balancer: Specify the value of the hosted zone ID for the load balancer. You can get the hosted zone ID by using the AWS Management Console, the ELB API, or the AWS CLI. Use the same method to get values for HostedZoneId and DNSName. If you get one value from the console and the other value from the API or the CLI, creating the resource record set will fail.
• An Amazon S3 bucket that is configured as a static website: Specify the hosted zone ID for the Amazon S3 website endpoint in which you created the bucket. For more information about valid values, see the table Amazon Simple Storage Service (S3) Website Endpoints in the Amazon Web Services General Reference.
• Another Amazon Route 53 resource record set in your hosted zone: Specify the hosted zone ID of your hosted zone. (An alias resource record set cannot reference a resource record set in a different hosted zone.)

For more information and an example, see Example: Creating Alias Resource Record Sets in the Amazon Route 53 API Reference.