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Amazon Route 53
Developer Guide (API Version 2013-04-01)

Values for Alias Resource Record Sets

When you create alias resource record sets, you specify the following values:

Name

Enter the name of the domain or subdomain for which you're creating the resource record set. The default value is the name of the hosted zone. If you're creating a resource record set that has the same name as the hosted zone, don't enter a value (for example, an @ symbol) in the Name field.

For information about how to specify characters other than a-z, 0-9, and - (hyphen) and how to specify internationalized domain names, see DNS Domain Name Format.

You can use an asterisk (*) character in the name. DNS treats the * character either as a wildcard or as the * character (ASCII 42), depending on where it appears in the name. For more information, see Using an Asterisk (*) in the Names of Hosted Zones and Resource Record Sets.

The value that you specify depends in part on the AWS resource for which you're creating an alias resource record set:

CloudFront Distributions

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.

Amazon S3 Buckets

The name of the resource record set must match the name of your Amazon S3 bucket. For example, if the name of your Amazon S3 bucket is acme.example.com, the name of this resource record set must also be acme.example.com.

In addition, you must configure the bucket for website hosting. For more information, see Configure a Bucket for Website Hosting in the Amazon Simple Storage Service Developer Guide.

Type

The DNS record type. For more information, see Supported DNS Resource Record Types.

Select the applicable value based on the AWS resource for which you're creating a resource record set:

CloudFront distribution

Select A — IPv4 address.

If IPv6 is enabled for the distribution, create two resource record sets, one with a value of A — IPv4 address for Type, and one with a value of AAAA — IPv6 address.

Elastic Beanstalk environment that has regionalized subdomains

Select A — IPv4 address

ELB load balancer

Select A — IPv4 address or AAAA — IPv6 address

Amazon S3 bucket

Select A — IPv4 address

Another resource record set in this hosted zone

Select the type of the resource record set for which you're creating the alias. Select any value except NS or SOA.

Alias

Select Yes.

Alias Target

The value that you specify depends on the AWS resource for which you're creating an alias resource record set.

CloudFront Distributions

Note

You can't create alias resource record sets for CloudFront distributions in a private hosted zone.

For CloudFront distributions, do one of the following:

  • If you used the same account to create your Amazon Route 53 hosted zone and your CloudFront distribution – Choose Alias Target and choose a distribution from the list. If you have a lot of distributions, you can type the first few characters of the domain name for your distribution to filter the list.

    If your distribution doesn't appear in the list, note the following:

    • The name of this resource record set must match an alternate domain name in your distribution.

    • If you just added an alternate domain name to your distribution, it may take 15 minutes for your changes to propagate to all CloudFront edge locations. Until changes have propagated, Amazon Route 53 can't know about the new alternate domain name.

  • If you used different accounts to create your Amazon Route 53 hosted zone and your distribution – Enter the CloudFront domain name for the distribution, such as d111111abcdef8.cloudfront.net.

    If you used one AWS account to create the current hosted zone and a different account to create a distribution, the distribution will not appear in the Alias Targets list.

    If you used one account to create the current hosted zone and one or more different accounts to create all of your distributions, the Alias Targets list shows No Targets Available under CloudFront Distributions.

Important

Do not route queries to a CloudFront distribution that has not propagated to all edge locations, or your users won't be able to access the applicable content.

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.

If IPv6 is enabled for the distribution, create two resource record sets, one with a value of A — IPv4 address for Type, and one with a value of AAAA — IPv6 address.

Elastic Beanstalk environments that have regionalized subdomains

For Elastic Beanstalk environments that have regionalized subdomains, do one of the following:

  • If you used the same account to create your Amazon Route 53 hosted zone and your Elastic Beanstalk environment – Choose Alias Target, and then choose an environment from the list. If you have a lot of environments, you can type the first few characters of the CNAME attribute for the environment to filter the list.

  • If you used different accounts to create your Amazon Route 53 hosted zone and your Elastic Beanstalk environment – Enter the CNAME attribute for the Elastic Beanstalk environment.

ELB Load Balancers

For ELB load balancers, do one of the following:

  • If you used the same account to create your Amazon Route 53 hosted zone and your load balancer – Choose Alias Target and choose a load balancer from the list. If you have a lot of load balancers, you can type the first few characters of the DNS name to filter the list.

  • If you used different accounts to create your Amazon Route 53 hosted zone and your load balancer – Enter the value that you got in the procedure Getting the DNS Name for an ELB Load Balancer.

    If you used one AWS account to create the current hosted zone and a different account to create a load balancer, the load balancer will not appear in the Alias Targets list.

    If you used one account to create the current hosted zone and one or more different accounts to create all of your load balancers, the Alias Targets list shows No Targets Available under Elastic Load Balancers.

In either case, the console prepends dualstack. to the DNS name. When a client, such as a web browser, requests the IP address for your domain name (example.com) or subdomain name (www.example.com), the client can request an IPv4 address (an A record), an IPv6 address (a AAAA record), or both IPv4 and IPv6 addresses (in separate requests). The dualstack. designation allows Amazon Route 53 to respond with the appropriate IP address for your load balancer based on which IP address format the client requested.

Amazon S3 Buckets

For Amazon S3 buckets that are configured as website endpoints, do one of the following:

  • If you used the same account to create your Amazon Route 53 hosted zone and your Amazon S3 bucket – Choose Alias Target and choose a bucket from the list. If you have a lot of buckets, you can type the first few characters of the DNS name to filter the list.

    The value of Alias Target changes to the Amazon S3 website endpoint for your bucket.

  • If you used different accounts to create your Amazon Route 53 hosted zone and your Amazon S3 bucket – Type the name of the region that you created your S3 bucket in. Use the value that appears in the Website Endpoint column in the Amazon Simple Storage Service Website Endpoints table in the AWS Regions and Endpoints chapter of the Amazon Web Services General Reference.

    If you used AWS accounts other than the current account to create your Amazon S3 buckets, the bucket won't appear in the Alias Targets list.

You must configure the bucket for website hosting. For more information, see Configure a Bucket for Website Hosting in the Amazon Simple Storage Service Developer Guide.

The name of the resource record set must match the name of your Amazon S3 bucket. For example, if the name of your Amazon S3 bucket is acme.example.com, the name of this resource record set must also be acme.example.com.

In a group of weighted alias, latency alias, failover alias, or geolocation alias resource record sets, you can create only one resource record set that routes queries to an Amazon S3 bucket because the name of the resource record set must match the name of the bucket and bucket names must be globally unique.

Resource Record Sets in this Hosted Zone

For resource record sets in this hosted zone, choose Alias Target and choose the applicable resource record set. If you have a lot of resource record sets, you can type the first few characters of the name to filter the list.

If the hosted zone contains only the default NS and SOA resource record sets, the Alias Targets list shows No Targets Available.

Alias Hosted Zone ID

This value appears automatically based on the value that you selected or entered for Alias Target.

Routing Policy

Select Simple.

Evaluate Target Health

Select Yes if you want Amazon Route 53 to determine whether to respond to DNS queries using this resource record set by checking the health of the resource record set specified by Alias Target.

Some AWS resources have special requirements:

  • CloudFront distributions – You cannot set Evaluate Target Health to Yes when the alias target is a CloudFront distribution.

  • Elastic Beanstalk environments that have regionalized endpoints – If you specify an Elastic Beanstalk environment in Alias Target and the environment contains an ELB load balancer, Elastic Load Balancing routes queries only to the healthy Amazon EC2 instances that are registered with the load balancer. (An environment automatically contains an ELB load balancer if it includes more than one Amazon EC2 instance.) If you set Evaluate Target Health to Yes and either no Amazon EC2 instances are healthy or the load balancer itself is unhealthy, Amazon Route 53 routes queries to other available resources that are healthy, if any.

    If the environment contains a single Amazon EC2 instance, there are no special requirements.

  • ELB load balancers – If you specify an ELB load balancer in Alias Target, Elastic Load Balancing routes queries only to the healthy Amazon EC2 instances that are registered with the load balancer. If you set Evaluate Target Health to Yes and either no Amazon EC2 instances are healthy or the load balancer itself is unhealthy, 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 Complex Amazon Route 53 Configurations.

  • Other resource record sets – If the AWS resource that you specify in Alias Target is a resource record set or a group of resource record sets (for example, a group of weighted resource record sets) but 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?.

We recommend that you set Evaluate Target Health to Yes only when you have enough idle capacity to handle the failure of one or more endpoints.