# AWS::RDS::DBSubnetGroup

The AWS::RDS::DBSubnetGroup resource creates a database subnet group. Subnet groups must contain at least two subnets in two different Availability Zones in the same region.

## Syntax

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

### JSON

<pre>
{
    "Type" : "AWS::RDS::DBSubnetGroup",
    "Properties" : {
        "<a href="#dbsubnetgroupdescription" title="DBSubnetGroupDescription">DBSubnetGroupDescription</a>" : <i>String</i>,
        "<a href="#dbsubnetgroupname" title="DBSubnetGroupName">DBSubnetGroupName</a>" : <i>String</i>,
        "<a href="#subnetids" title="SubnetIds">SubnetIds</a>" : <i>[ String, ... ]</i>,
        "<a href="#tags" title="Tags">Tags</a>" : <i>[ <a href="tag.md">Tag</a>, ... ]</i>
    }
}
</pre>

### YAML

<pre>
Type: AWS::RDS::DBSubnetGroup
Properties:
    <a href="#dbsubnetgroupdescription" title="DBSubnetGroupDescription">DBSubnetGroupDescription</a>: <i>String</i>
    <a href="#dbsubnetgroupname" title="DBSubnetGroupName">DBSubnetGroupName</a>: <i>String</i>
    <a href="#subnetids" title="SubnetIds">SubnetIds</a>: <i>
      - String</i>
    <a href="#tags" title="Tags">Tags</a>: <i>
      - <a href="tag.md">Tag</a></i>
</pre>

## Properties

#### DBSubnetGroupDescription

_Required_: Yes

_Type_: String

_Update requires_: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

#### DBSubnetGroupName

_Required_: No

_Type_: String

_Pattern_: <code>^(?!default$)[a-zA-Z]{1}[a-zA-Z0-9-_\.\s]{0,254}$</code>

_Update requires_: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

#### SubnetIds

_Required_: Yes

_Type_: List of String

_Update requires_: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

#### Tags

An array of key-value pairs to apply to this resource.

_Required_: No

_Type_: List of <a href="tag.md">Tag</a>

_Update requires_: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## Return Values

### Ref

When you pass the logical ID of this resource to the intrinsic `Ref` function, Ref returns the DBSubnetGroupName.