This is the new *CloudFormation Template Reference Guide*. Please update your bookmarks and links. For help getting started with CloudFormation, see the [AWS CloudFormation User Guide](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/Welcome.html).

# AWS::ServiceDiscovery::Service DnsRecord
<a name="aws-properties-servicediscovery-service-dnsrecord"></a>

A complex type that contains information about the Route 53 DNS records that you want AWS Cloud Map to create when you register an instance.

## Syntax
<a name="aws-properties-servicediscovery-service-dnsrecord-syntax"></a>

To declare this entity in your CloudFormation template, use the following syntax:

### JSON
<a name="aws-properties-servicediscovery-service-dnsrecord-syntax.json"></a>

```
{
  "[TTL](#cfn-servicediscovery-service-dnsrecord-ttl)" : {{Number}},
  "[Type](#cfn-servicediscovery-service-dnsrecord-type)" : {{String}}
}
```

### YAML
<a name="aws-properties-servicediscovery-service-dnsrecord-syntax.yaml"></a>

```
  [TTL](#cfn-servicediscovery-service-dnsrecord-ttl): {{Number}}
  [Type](#cfn-servicediscovery-service-dnsrecord-type): {{String}}
```

## Properties
<a name="aws-properties-servicediscovery-service-dnsrecord-properties"></a>

`TTL`  <a name="cfn-servicediscovery-service-dnsrecord-ttl"></a>
The amount of time, in seconds, that you want DNS resolvers to cache the settings for this record.  
Alias records don't include a TTL because Route 53 uses the TTL for the AWS resource that an alias record routes traffic to. If you include the `AWS_ALIAS_DNS_NAME` attribute when you submit a [RegisterInstance](https://docs.aws.amazon.com/cloud-map/latest/api/API_RegisterInstance.html) request, the `TTL` value is ignored. Always specify a TTL for the service; you can use a service to register instances that create either alias or non-alias records.
*Required*: Yes  
*Type*: Number  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Type`  <a name="cfn-servicediscovery-service-dnsrecord-type"></a>
The type of the resource, which indicates the type of value that Route 53 returns in response to DNS queries. You can specify values for `Type` in the following combinations:  
+  `A` 
+  `AAAA` 
+ `A` and `AAAA`
+  `SRV` 
+  `CNAME` 
If you want AWS Cloud Map to create a Route 53 alias record when you register an instance, specify `A` or `AAAA` for `Type`.  
You specify other settings, such as the IP address for `A` and `AAAA` records, when you register an instance. For more information, see [RegisterInstance](https://docs.aws.amazon.com/cloud-map/latest/api/API_RegisterInstance.html).  
The following values are supported:    
A  
Route 53 returns the IP address of the resource in IPv4 format, such as 192.0.2.44.  
AAAA  
Route 53 returns the IP address of the resource in IPv6 format, such as 2001:0db8:85a3:0000:0000:abcd:0001:2345.  
CNAME  
Route 53 returns the domain name of the resource, such as www.example.com. Note the following:  
+ You specify the domain name that you want to route traffic to when you register an instance. For more information, see [Attributes](https://docs.aws.amazon.com/cloud-map/latest/api/API_RegisterInstance.html#cloudmap-RegisterInstance-request-Attributes) in the topic [RegisterInstance](https://docs.aws.amazon.com/cloud-map/latest/api/API_RegisterInstance.html).
+ You must specify `WEIGHTED` for the value of `RoutingPolicy`.
+ You can't specify both `CNAME` for `Type` and settings for `HealthCheckConfig`. If you do, the request will fail with an `InvalidInput` error.  
SRV  
Route 53 returns the value for an `SRV` record. The value for an `SRV` record uses the following values:  
 `priority weight port service-hostname`   
Note the following about the values:  
+ The values of `priority` and `weight` are both set to `1` and can't be changed. 
+ The value of `port` comes from the value that you specify for the `AWS_INSTANCE_PORT` attribute when you submit a [RegisterInstance](https://docs.aws.amazon.com/cloud-map/latest/api/API_RegisterInstance.html) request. 
+ The value of `service-hostname` is a concatenation of the following values:
  + The value that you specify for `InstanceId` when you register an instance.
  + The name of the service.
  + The name of the namespace. 

  For example, if the value of `InstanceId` is `test`, the name of the service is `backend`, and the name of the namespace is `example.com`, the value of `service-hostname` is:

   `test.backend.example.com` 
If you specify settings for an `SRV` record and if you specify values for `AWS_INSTANCE_IPV4`, `AWS_INSTANCE_IPV6`, or both in the `RegisterInstance` request, AWS Cloud Map automatically creates `A` and/or `AAAA` records that have the same name as the value of `service-hostname` in the `SRV` record. You can ignore these records.
*Required*: Yes  
*Type*: String  
*Allowed values*: `SRV | A | AAAA | CNAME`  
*Update requires*: Updates are not supported.

## See also
<a name="aws-properties-servicediscovery-service-dnsrecord--seealso"></a>
+ [Return values](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-servicediscovery-service.html#aws-resource-servicediscovery-service-return-values) in the topic [AWS::ServiceDiscovery::Service](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-servicediscovery-service.html)
+ [DnsRecord](https://docs.aws.amazon.com/cloud-map/latest/api/API_DnsRecord.html) in the *AWS Cloud Map API Reference*