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::EC2::DHCPOptions
<a name="aws-resource-ec2-dhcpoptions"></a>

Specifies a set of DHCP options for your VPC.

You must specify at least one of the following properties: `DomainNameServers`, `NetbiosNameServers`, `NtpServers`. If you specify `NetbiosNameServers`, you must specify `NetbiosNodeType`.

## Syntax
<a name="aws-resource-ec2-dhcpoptions-syntax"></a>

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

### JSON
<a name="aws-resource-ec2-dhcpoptions-syntax.json"></a>

```
{
  "Type" : "AWS::EC2::DHCPOptions",
  "Properties" : {
      "[DomainName](#cfn-ec2-dhcpoptions-domainname)" : String,
      "[DomainNameServers](#cfn-ec2-dhcpoptions-domainnameservers)" : [ String, ... ],
      "[Ipv6AddressPreferredLeaseTime](#cfn-ec2-dhcpoptions-ipv6addresspreferredleasetime)" : Integer,
      "[NetbiosNameServers](#cfn-ec2-dhcpoptions-netbiosnameservers)" : [ String, ... ],
      "[NetbiosNodeType](#cfn-ec2-dhcpoptions-netbiosnodetype)" : Integer,
      "[NtpServers](#cfn-ec2-dhcpoptions-ntpservers)" : [ String, ... ],
      "[Tags](#cfn-ec2-dhcpoptions-tags)" : [ Tag, ... ]
    }
}
```

### YAML
<a name="aws-resource-ec2-dhcpoptions-syntax.yaml"></a>

```
Type: AWS::EC2::DHCPOptions
Properties:
  [DomainName](#cfn-ec2-dhcpoptions-domainname): String
  [DomainNameServers](#cfn-ec2-dhcpoptions-domainnameservers): 
    - String
  [Ipv6AddressPreferredLeaseTime](#cfn-ec2-dhcpoptions-ipv6addresspreferredleasetime): Integer
  [NetbiosNameServers](#cfn-ec2-dhcpoptions-netbiosnameservers): 
    - String
  [NetbiosNodeType](#cfn-ec2-dhcpoptions-netbiosnodetype): Integer
  [NtpServers](#cfn-ec2-dhcpoptions-ntpservers): 
    - String
  [Tags](#cfn-ec2-dhcpoptions-tags): 
    - Tag
```

## Properties
<a name="aws-resource-ec2-dhcpoptions-properties"></a>

`DomainName`  <a name="cfn-ec2-dhcpoptions-domainname"></a>
This value is used to complete unqualified DNS hostnames. If you're using AmazonProvidedDNS in `us-east-1`, specify `ec2.internal`. If you're using AmazonProvidedDNS in another Region, specify *region*.`compute.internal` (for example, `ap-northeast-1.compute.internal`). Otherwise, specify a domain name (for example, *MyCompany.com*).  
*Required*: No  
*Type*: String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`DomainNameServers`  <a name="cfn-ec2-dhcpoptions-domainnameservers"></a>
The IPv4 addresses of up to four domain name servers, or `AmazonProvidedDNS`. The default is `AmazonProvidedDNS`. To have your instance receive a custom DNS hostname as specified in `DomainName`, you must set this property to a custom DNS server.  
*Required*: Conditional  
*Type*: Array of String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Ipv6AddressPreferredLeaseTime`  <a name="cfn-ec2-dhcpoptions-ipv6addresspreferredleasetime"></a>
A value (in seconds, minutes, hours, or years) for how frequently a running instance with an IPv6 assigned to it goes through DHCPv6 lease renewal. Acceptable values are between 140 and 2147483647 seconds (approximately 68 years). If no value is entered, the default lease time is 140 seconds. If you use long-term addressing for EC2 instances, you can increase the lease time and avoid frequent lease renewal requests. Lease renewal typically occurs when half of the lease time has elapsed.   
*Required*: No  
*Type*: Integer  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`NetbiosNameServers`  <a name="cfn-ec2-dhcpoptions-netbiosnameservers"></a>
The IPv4 addresses of up to four NetBIOS name servers.  
*Required*: Conditional  
*Type*: Array of String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`NetbiosNodeType`  <a name="cfn-ec2-dhcpoptions-netbiosnodetype"></a>
The NetBIOS node type (1, 2, 4, or 8). We recommend that you specify 2 (broadcast and multicast are not currently supported).  
*Required*: No  
*Type*: Integer  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`NtpServers`  <a name="cfn-ec2-dhcpoptions-ntpservers"></a>
The IPv4 addresses of up to four Network Time Protocol (NTP) servers.  
*Required*: Conditional  
*Type*: Array of String  
*Update requires*: [Replacement](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-replacement)

`Tags`  <a name="cfn-ec2-dhcpoptions-tags"></a>
Any tags assigned to the DHCP options set.  
*Required*: No  
*Type*: Array of [Tag](aws-properties-ec2-dhcpoptions-tag.md)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## Return values
<a name="aws-resource-ec2-dhcpoptions-return-values"></a>

### Ref
<a name="aws-resource-ec2-dhcpoptions-return-values-ref"></a>

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

For more information about using the `Ref` function, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-ref.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-ref.html).

### Fn::GetAtt
<a name="aws-resource-ec2-dhcpoptions-return-values-fn--getatt"></a>

The `Fn::GetAtt` intrinsic function returns a value for a specified attribute of this type. The following are the available attributes and sample return values.

For more information about using the `Fn::GetAtt` intrinsic function, see [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-getatt.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/intrinsic-function-reference-getatt.html).

#### 
<a name="aws-resource-ec2-dhcpoptions-return-values-fn--getatt-fn--getatt"></a>

`DhcpOptionsId`  <a name="DhcpOptionsId-fn::getatt"></a>
The ID of the DHCP options set.

## Examples
<a name="aws-resource-ec2-dhcpoptions--examples"></a>

### Create a DHCP options set
<a name="aws-resource-ec2-dhcpoptions--examples--Create_a_DHCP_options_set"></a>

The following example creates a DHCP options set.

#### YAML
<a name="aws-resource-ec2-dhcpoptions--examples--Create_a_DHCP_options_set--yaml"></a>

```
myDhcpOptions: 
    Type: AWS::EC2::DHCPOptions
    Properties: 
        DomainName: example.com
        DomainNameServers: 
          - AmazonProvidedDNS
        NtpServers: 
          - 10.2.5.1
        NetbiosNameServers: 
          - 10.2.5.1
        NetbiosNodeType: 2
        Tags: 
        - Key: project
          Value: 123
```

#### JSON
<a name="aws-resource-ec2-dhcpoptions--examples--Create_a_DHCP_options_set--json"></a>

```
{
    "myDhcpOptions" : {
        "Type" : "AWS::EC2::DHCPOptions",
        "Properties" : {
            "DomainName" : "example.com",
            "DomainNameServers" : [ "AmazonProvidedDNS" ],
            "NtpServers" : [ "10.2.5.1" ],
            "NetbiosNameServers" : [ "10.2.5.1" ],
            "NetbiosNodeType" : 2,
            "Tags" : [ { "Key" : "project", "Value" : "123" } ]
        }
    }
}
```

## See also
<a name="aws-resource-ec2-dhcpoptions--seealso"></a>
+ [CreateDhcpOptions](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/ApiReference-query-CreateDhcpOptions.html) in the *Amazon EC2 API Reference*
+ [DHCP options sets](https://docs.aws.amazon.com/vpc/latest/userguide/VPC_DHCP_Options.html) in the *Amazon VPC User Guide*



# AWS::EC2::DHCPOptions Tag
<a name="aws-properties-ec2-dhcpoptions-tag"></a>

Specifies a tag. For more information, see [Resource tags](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-resource-tags.html).

## Syntax
<a name="aws-properties-ec2-dhcpoptions-tag-syntax"></a>

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

### JSON
<a name="aws-properties-ec2-dhcpoptions-tag-syntax.json"></a>

```
{
  "[Key](#cfn-ec2-dhcpoptions-tag-key)" : String,
  "[Value](#cfn-ec2-dhcpoptions-tag-value)" : String
}
```

### YAML
<a name="aws-properties-ec2-dhcpoptions-tag-syntax.yaml"></a>

```
  [Key](#cfn-ec2-dhcpoptions-tag-key): String
  [Value](#cfn-ec2-dhcpoptions-tag-value): String
```

## Properties
<a name="aws-properties-ec2-dhcpoptions-tag-properties"></a>

`Key`  <a name="cfn-ec2-dhcpoptions-tag-key"></a>
The tag key.  
*Required*: Yes  
*Type*: String  
*Minimum*: `1`  
*Maximum*: `128`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Value`  <a name="cfn-ec2-dhcpoptions-tag-value"></a>
The tag value.  
*Required*: Yes  
*Type*: String  
*Minimum*: `0`  
*Maximum*: `256`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

## Examples
<a name="aws-properties-ec2-dhcpoptions-tag--examples"></a>

### 
<a name="aws-properties-ec2-dhcpoptions-tag--examples--"></a>

This example specifies two tags for the set of DHCP options.

#### JSON
<a name="aws-properties-ec2-dhcpoptions-tag--examples----json"></a>

```
"Tags" : [
   {
      "Key" : "key1",
      "Value" : "value1"
   },
   {
      "Key" : "key2",
      "Value" : "value2"
   }
]
```

#### YAML
<a name="aws-properties-ec2-dhcpoptions-tag--examples----yaml"></a>

```
Tags: 
  - Key: "key1"
    Value: "value1"
  - Key: "key2"
    Value: "value2"
```