Applies only to alias, failover alias, geolocation alias, latency alias, and weighted alias resource record
sets: When EvaluateTargetHealth
is true
, an alias resource record set inherits the
health of the referenced AWS resource, such as an ELB load balancer or another resource record set in the hosted
zone.
Note the following:
CloudFront distributions
You can't set EvaluateTargetHealth
to true
when the alias target is a CloudFront
distribution.
Elastic Beanstalk environments that have regionalized subdomains
If you specify an Elastic Beanstalk environment in DNSName
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 EvaluateTargetHealth
to true
and either no Amazon EC2
instances are healthy or the load balancer itself is unhealthy, 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
Health checking behavior depends on the type of load balancer:
-
Classic Load Balancers: If you specify an ELB Classic Load Balancer in DNSName
, Elastic Load
Balancing routes queries only to the healthy Amazon EC2 instances that are registered with the load balancer. If
you set EvaluateTargetHealth
to true
and either no EC2 instances are healthy or the
load balancer itself is unhealthy, Route 53 routes queries to other resources.
-
Application and Network Load Balancers: If you specify an ELB Application or Network Load Balancer and you
set EvaluateTargetHealth
to true
, Route 53 routes queries to the load balancer based on
the health of the target groups that are associated with the load balancer:
-
For an Application or Network Load Balancer to be considered healthy, every target group that contains targets
must contain at least one healthy target. If any target group contains only unhealthy targets, the load balancer
is considered unhealthy, and Route 53 routes queries to other resources.
-
A target group that has no registered targets is considered healthy.
When you create a load balancer, you configure settings for Elastic Load Balancing health checks; they're not
Route 53 health checks, but they perform a similar function. Do not create Route 53 health checks for the EC2
instances that you register with an ELB load balancer.
S3 buckets
There are no special requirements for setting EvaluateTargetHealth
to true
when the
alias target is an S3 bucket.
Other records in the same hosted zone
If the AWS resource that you specify in DNSName
is a record or a group of records (for example, a
group of weighted records) but is not another alias record, we recommend that you associate a health check with
all of the records in the alias target. For more information, see What Happens When You Omit Health Checks? in the Amazon Route 53 Developer Guide.
For more information and examples, see Amazon Route 53 Health Checks
and DNS Failover in the Amazon Route 53 Developer Guide.