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# AWS::ServiceDiscovery::PublicDnsNamespace SOA
<a name="aws-properties-servicediscovery-publicdnsnamespace-soa"></a>

Start of Authority (SOA) properties for a public or private DNS namespace.

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

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

```
{
  "[TTL](#cfn-servicediscovery-publicdnsnamespace-soa-ttl)" : Number
}
```

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

```
  [TTL](#cfn-servicediscovery-publicdnsnamespace-soa-ttl): Number
```

## Properties
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`TTL`  <a name="cfn-servicediscovery-publicdnsnamespace-soa-ttl"></a>
The time to live (TTL) for purposes of negative caching.  
*Required*: No  
*Type*: Number  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)