> ## Documentation Index
> Fetch the complete documentation index at: https://docs.coreweave.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Virtual Private Clouds (VPCs)

> Virtual Private Clouds provide network isolation and custom addressing for CKS clusters

CoreWeave Virtual Private Clouds (<Tooltip tip="A Virtual Private Cloud (VPC) is a private network hosted within a public cloud infrastructure." cta="Learn more" href="/glossary#virtual-private-cloud-vpc">VPCs</Tooltip>) define the network isolation configuration for attached CoreWeave products, like [CKS clusters](/products/cks/clusters/introduction). VPCs let clusters securely communicate with resources in a <Tooltip tip="A region encompasses a broader geographic area, expanding service availability and meeting data residency requirements." cta="Learn more" href="/glossary#region">Region</Tooltip>, and with the public internet if desired, while preserving the privacy and security of the cluster's network.

This page introduces how CoreWeave VPCs work, the default VPC behavior for new CKS clusters, the prefix types you can configure, and when to define a custom VPC.

## Default VPCs

When you create your first CKS cluster through the Cloud Console, CoreWeave creates a default VPC in the same Zone as that cluster, unless you define a custom VPC. This default ensures that clusters have working network isolation without requiring upfront VPC configuration.

### Custom prefixes

You can add custom VPC Prefixes to custom or default VPCs to allow communication with other VPCs in the same Region, with remote cloud providers, or with on-premises networks through a VPN or Direct Connect. Configure custom prefixes when your workloads need to reach networks outside the VPC. Add custom prefixes to a VPC [through the Cloud Console during VPC creation](/products/networking/vpc/create-manage-vpcs#vpc-prefixes), or [during cluster creation at the network configuration step](/products/cks/clusters/create#select-a-vpc).

You can configure two types of prefixes for VPCs:

| Prefix type       | Description                                                                                                                                                                       |
| ----------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Host Prefixes** | A range of IP addresses to assign to the Nodes within a VPC. Nodes use these addresses for network communications with other resources within the VPC.                            |
| **VPC Prefixes**  | A range of IP addresses you can use to communicate with other VPCs in the same Region, with remote cloud providers, or with on-premises networks through a VPN or Direct Connect. |

Each CoreWeave <Tooltip tip="An Availability Zone (AZ) is a partition within a region that hosts one or more data halls. AZs are physically and operationally independent from each other." cta="Learn more" href="/glossary#availability-zone-az">Availability Zone (AZ)</Tooltip> has a default Host Prefix, which CoreWeave assigns automatically unless you specify a different prefix.

The default Host Prefixes for each AZ are:

| General Access AZ                                               | Default Host Prefix CIDR |
| --------------------------------------------------------------- | ------------------------ |
| [`EU-SOUTH-03B`](/platform/regions/eu-south#eu-south-03b)       | `10.206.192.0/18`        |
| [`EU-SOUTH-04A`](/platform/regions/eu-south#eu-south-04a)       | `10.104.192.0/18`        |
| [`RNO2A`](/platform/regions/us-west#rno2a)                      | `10.168.192.0/18`        |
| [`US-CENTRAL-06A`](/platform/regions/us-central#us-central-06a) | `10.50.192.0/18`         |
| [`US-CENTRAL-07A`](/platform/regions/us-central#us-central-07a) | `10.109.128.0/18`        |
| [`US-EAST-01A`](/platform/regions/us-east#us-east-01a)          | `10.202.192.0/18`        |
| [`US-EAST-02A`](/platform/regions/us-east#us-east-02a)          | `10.184.192.0/18`        |
| [`US-EAST-04A`](/platform/regions/us-east#us-east-04a)          | `10.176.192.0/18`        |
| [`US-EAST-06A`](/platform/regions/us-east#us-east-06a)          | `10.192.192.0/18`        |
| [`US-EAST-08A`](/platform/regions/us-east#us-east-08a)          | `10.186.192.0/18`        |
| [`US-EAST-13A`](/platform/regions/us-east#us-east-13a)          | `10.221.128.0/18`        |
| [`US-EAST-14A`](/platform/regions/us-east#us-east-14a)          | `10.213.128.0/18`        |
| [`US-WEST-01A`](/platform/regions/us-west#us-west-01a)          | `10.188.192.0/18`        |
| [`US-WEST-04A`](/platform/regions/us-west#us-west-04a)          | `10.190.192.0/18`        |
| [`US-WEST-09B`](/platform/regions/us-west#us-west-09b)          | `10.210.192.0/18`        |
| [`US-WEST-10A`](/platform/regions/us-west#us-west-10a)          | `10.57.128.0/17`         |

<Info>
  You can't modify or remove Host Prefixes after you add them to a VPC. CoreWeave assigns Host Prefixes when the Node boots, so you can't modify them while the Node is running.
</Info>

### Default VPC names

CoreWeave automatically creates a default VPC when you first create a cluster. The name of a new default VPC uses the following format:

`cw-vpc-[CLUSTER-NAME]-[SIX-DIGIT-STRING]`

To see the name of the default VPC, click the **Customize** option beside the default VPC selector during [cluster creation](/products/cks/clusters/create#2-network).

## Custom VPCs

When the default VPC doesn't meet your network requirements, for example when you need custom addressing or connectivity to external networks, define a custom VPC instead. If you need a custom VPC configuration, define it by [creating a VPC](/products/networking/vpc/create-manage-vpcs) from the Cloud Console, or during the cluster creation process by [defining a custom VPC](/products/cks/clusters/create#select-a-vpc).

For more information, see [VPC API reference](/products/networking/vpc/vpc-api).