AWS SDK Version 3 for .NET
API Reference

AWS services or capabilities described in AWS Documentation may vary by region/location. Click Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

Creates a subnet in an existing VPC.

When you create each subnet, you provide the VPC ID and IPv4 CIDR block for the subnet. After you create a subnet, you can't change its CIDR block. The size of the subnet's IPv4 CIDR block can be the same as a VPC's IPv4 CIDR block, or a subset of a VPC's IPv4 CIDR block. If you create more than one subnet in a VPC, the subnets' CIDR blocks must not overlap. The smallest IPv4 subnet (and VPC) you can create uses a /28 netmask (16 IPv4 addresses), and the largest uses a /16 netmask (65,536 IPv4 addresses).

If you've associated an IPv6 CIDR block with your VPC, you can create a subnet with an IPv6 CIDR block that uses a /64 prefix length.

AWS reserves both the first four and the last IPv4 address in each subnet's CIDR block. They're not available for use.

If you add more than one subnet to a VPC, they're set up in a star topology with a logical router in the middle.

If you launch an instance in a VPC using an Amazon EBS-backed AMI, the IP address doesn't change if you stop and restart the instance (unlike a similar instance launched outside a VPC, which gets a new IP address when restarted). It's therefore possible to have a subnet with no running instances (they're all stopped), but no remaining IP addresses available.

For more information about subnets, see Your VPC and Subnets in the Amazon Virtual Private Cloud User Guide.


For .NET Core and PCL this operation is only available in asynchronous form. Please refer to CreateSubnetAsync.

Namespace: Amazon.EC2
Assembly: AWSSDK.EC2.dll
Version: 3.x.y.z


public abstract CreateSubnetResponse CreateSubnet(
         CreateSubnetRequest request
Type: Amazon.EC2.Model.CreateSubnetRequest

Container for the necessary parameters to execute the CreateSubnet service method.

Return Value
The response from the CreateSubnet service method, as returned by EC2.


This example creates a subnet in the specified VPC with the specified CIDR block. We recommend that you let us select an Availability Zone for you.

To create a subnet

var response = client.CreateSubnet(new CreateSubnetRequest 
    CidrBlock = "",
    VpcId = "vpc-a01106c2"

Subnet subnet = response.Subnet;


Version Information

.NET Framework:
Supported in: 4.5, 4.0, 3.5

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms

See Also