Subnets

Subnets are logical subdivisions within a VPC's IP address range. They enable segmentation of the network and provide a way to organize and control access to your resources.

We recommended that you create separate subnets for external and internal use.

  • An external, or frontend subnet serves as the entry point of your network of servers. Use it to host resources that you need to be publicly available, such as your web servers or public-facing APIs. You can configure the security group of this subnet to allow public access.

  • An internal, or backend subnet ensures that your sensitive resources and internal services are protected form public access. Use it to host resources that should only communicate internally within your network, such as your databases or internal application servers. You can configure the security group of this subnet to deny public access, and only allow traffic from your frontend subnet, or other trusted IP address ranges.

Create subnets

You can create subnets in 2 ways:

  • On the details page of VPCs you already created
  • During the server creation flow

The CIDR block you specify for a subnet is permanent and cannot be modified after creation.

When you create a subnet, you need to define a name, the IPv4 CIDR block, and a gateway IP address. Divide the VPC’s CIDR block into smaller, non-overlapping subnet ranges based on your application needs.

We recommend that you assign the first IP address in your subnet's address range as the gateway address. This address serves as the entry and exit for your subnet. If the gateway address you select falls outside the subnet's range, the Console returns an error.

Nebula automatically reserves the last IP address in a subnet's address range as a broadcast address. This address enables synchronized communication to all addresses within the subnet's network.

Manage subnets

You can manage your subnets via the details page of the VPC that the subnet is attached to.

Select a VPC, then the subnet you want to manage to see details like:

  • the assigned CIDR block
  • the subnet's ID
  • the gateway IP
  • the attached server instances

You can delete subnets on the subnet details screen.

You can only delete subnets that have no associated resources. First, terminate any server instances within the subnet, then delete the subnet itself.

Need help?

If you have any technical questions or encounter any problems, get in touch with our Support team! We're here to help, and will provide support if you encounter any issues with NebCompute.

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