> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/api-reference/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/api-reference/bmc/vpc/subnet/createsubnet.md).

# CreateSubnet

## 1. API Description

This API (CreateSubnet) is used to create a subnet.

#### Prerequisites

Before creating a subnet, call [`DescribeSubnetAvailableResources`](/api-reference/bmc/vpc/subnet/describesubnetavailableresources.md) to check the zones available for subnet creation.

{% hint style="info" %} <mark style="color:blue;">**Note**</mark>

* <mark style="color:blue;">The quantity of subnets you can create in one zone is limited. If you need more, please contact Zenlayer Support.</mark>
* <mark style="color:blue;">Create a subnet separately if you need a Layer 2 network; create subnets in a VPC if you need a Layer 3 network. You are recommended to create subnets in a VPC because they can communicate with each other. You can also create a subnet separately and then upgrade it into a VPC.</mark>
* <mark style="color:blue;">This API is an async API. A subnet ID list is returned after the creation request is sent. However, it does not mean the creation has been completed. The status of the subnet will be</mark> <mark style="color:blue;">`CREATING`</mark> <mark style="color:blue;">during the creation. You can use</mark> [<mark style="color:blue;"><mark style="color:purple;">`DescribeSubnets`<mark style="color:purple;"></mark>](/api-reference/bmc/vpc/subnet/describesubnets.md) <mark style="color:blue;">to query the status of the subnet. If the status changes from</mark> <mark style="color:blue;">`Creating`</mark> <mark style="color:blue;">to</mark> <mark style="color:blue;">`Available`</mark><mark style="color:blue;">, it means that the subnet has been created successfully;</mark> <mark style="color:blue;">`CREATE_FAILED`</mark> <mark style="color:blue;">means the subnet has been created failed. Any operations on the subnets are not allowed while creating.</mark>
  {% endhint %}

## 2. Input Parameters

The following request parameter list only provides API request parameters.

| Parameter Name  | Required | Type   | Description                                                                                                                                                                                                                                                                                                                                            |
| --------------- | -------- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| zoneId          | Yes      | String | Zone ID to which the subnet belongs.                                                                                                                                                                                                                                                                                                                   |
| cidrBlock       | Yes      | String | <p>CIDR block of the subnet. The optional values are as follows:</p><p>10.0.0.0/16 , 172.16.0.0/16 , 192.168.0.0/16 and their subsets.</p><p>If the subnet is going to be added into a VPC, the value should be in the range of VPC CIDR block and not overlap with IP ranges of other subnets in this VPC.</p>                                        |
| subnetName      | Yes      | String | <p>Subnet name to be displayed.</p><p>This parameter can contain up to 64 characters. Only letters, numbers, - and periods (.) are supported.</p>                                                                                                                                                                                                      |
| resourceGroupId | No       | String | <p>Resource group ID.</p><p>If the value is not passed in, the subnet will be put into the default resource group. If no authorized default resource group found, the request will fail.</p><p>If the subnet is going to be added into a VPC, this parameter will be ignored. The created subnet will be added into the resource group of the VPC.</p> |
| vpcId           | No       | String | VPC ID.                                                                                                                                                                                                                                                                                                                                                |

## 3. Output Parameters

| Parameter Name | Type   | Description                                                                                                           |
| -------------- | ------ | --------------------------------------------------------------------------------------------------------------------- |
| requestId      | String | <p>The unique request ID, which is returned for each request.</p><p>RequestId is required for locating a problem.</p> |
| subnetId       | String | Subnet ID.                                                                                                            |

## 4. Code Example

{% tabs %}
{% tab title="Example" %}
Create a subnet in zone `SIN-B`.

<pre class="language-json"><code class="lang-json"><strong>POST /api/v2/bmc HTTP/1.1
</strong>Host: console.zenlayer.com
Content-Type: application/json
X-ZC-Action: CreateSubnet


Request:
{
  "zoneId": "SIN-B",
  "cidrBlock": "10.0.0.0/16",
  "subnetName": "Subnet-Test-alict"
}

Response:
{
  "requestId": "T39EC84B4-63B4-409E-A09D-F052434DF276",
  "response": {
    "requestId": "T39EC84B4-63B4-409E-A09D-F052434DF276",
    "subnetId": "832999436413042904"
  }
}
</code></pre>

{% endtab %}
{% endtabs %}

## 5. Developer Resources

Zenlayer Cloud API 2.0 integrates [SDKs](/api-reference/api-introduction/toolkit/api-sdk.md)，to make it easier for you to call APIs. More programming languages will be supported.

## 6. Error Codes

The following only lists the error codes related to the API business logic. For other error codes, see [Common Error Codes](/api-reference/api-introduction/instruction/commonerrorcode.md).

| HTTP Status Code | Error Code                                          | Description                                                        |
| ---------------- | --------------------------------------------------- | ------------------------------------------------------------------ |
| 403              | OPERATION\_DENIED\_VPC\_ZONE\_SUBNET\_EXCEED\_LIMIT | Quantity of subnets exceeds the limit of the zone.                 |
| 403              | OPERATION\_DENIED\_SUBNET\_EXCEED\_LIMIT            | The number of availability zones for the subnet exceeds the limit. |
| 404              | INVALID\_ZONE\_NOT\_FOUND                           | Zone not found.                                                    |
| 400              | INVALID\_PARAMETER\_SUBNET\_CIDR\_NOT\_BELONG\_VPC  | The subnet IP range does not belong to the VPC IP range.           |
| 403              | OPERATION\_DENIED\_NO\_AVAILABLE\_VPC\_REGION       | Invalid availability region ID of VPC.                             |
| 403              | OPERATION\_DENIED\_ZONE\_NOT\_BELONG\_VPC           | Zone of subnet does not belong to the availability region of VPC.  |
| 400              | INVALID\_PARAMETER\_SUBNET\_LAN\_IP                 | CIDR block is not within a private network range.                  |
| 404              | INVALID\_VPC\_NOT\_FOUND                            | VPC not found.                                                     |
| 400              | INVALID\_PARAMETER\_SUBNET\_CIDR\_BLOCK             | Invalid CIDR block format.                                         |
| 403              | OPERATION\_DENIED\_VPC\_STATUS\_NOT\_SUPPORT        | VPC status not supported.                                          |
| 400              | INVALID\_PARAMETER\_VPC\_SUBNET\_OVER\_LAP          | Overlapped CIDR blocks of subnets in VPC.                          |
| 400              | INVALID\_PARAMETER\_SUBNET\_LAN\_IP\_NETMASK        | Invalid CIDR block netmask range.                                  |
| 403              | OPERATION\_DENIED\_ZONE\_NOT\_SUPPORT\_SUBNET       | The availability zone does not support creating subnets.           |