> 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/cidr-block/releasecidrblocks.md).

# ReleaseCidrBlocks

## 1. API Description

This API (ReleaseCidrBlocks) is used to release one or more IPv4 CIDR blocks.

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

* <mark style="color:blue;">IPv4 CIDR blocks</mark> <mark style="color:blue;">in recycle bin are remained for 24 hours by default.</mark>
* <mark style="color:blue;">Only operations on</mark> <mark style="color:blue;">IPv4 CIDR blocks in recycle bin with the status of</mark> <mark style="color:blue;">`RECYCLE`</mark> <mark style="color:blue;">are supported.</mark>
* <mark style="color:blue;">This API is not applicable to IPv6 CIDR block.</mark>
* <mark style="color:blue;">Batch operations are supported. The maximum number of instances in each request is 100.</mark>
  {% endhint %}

## 2. Input Parameters

The following request parameter list only provides API request parameters.

| Parameter Name | Required | Type            | Description                                                                                                                                                                                            |
| -------------- | -------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| cidrBlockIds   | Yes      | Array of String | <p>CIDR block ID(s).</p><p>To obtain the CIDR block IDs, you can call DescribeCidrBlocks and look for cidrBlockId in the response.</p><p>The maximum number of CIDR blocks in each request is 100.</p> |

## 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> |

## 4. Code Example

{% tabs %}
{% tab title="Example" %}
Release IPv4 CIDR blocks.

```json
POST /api/v2/bmc HTTP/1.1
Host: console.zenlayer.com
Content-Type: application/json
X-ZC-Action: ReleaseCidrBlocks
<Common Request Params>

Request:
{
  "cidrBlockIds": [
    "cidrBlockId1",
    "cidrBlockId2"
  ]
}

Response:
{
  "requestId": "TF7DE750F-B3AA-4A65-BB46-1EE89072FC04",
  "response": {
    "requestId": "TF7DE750F-B3AA-4A65-BB46-1EE89072FC04"
  }
}
```

{% 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\_CIDRBLOCK\_NOT\_RECYCLED | This operation is not supported for CIDR block not in the recycle bin. |