You can use default VPC networks and VSwitches when you create Elastic Compute Service (ECS) instances, Server Load Balancer (SLB) instances, and ApsaraDB for RDS instances. If you have not created a default VPC network or VSwitch, they are automatically created after you create an ECS, SLB, or ApsaraDB for RDS instance.

Default VPC networks and VSwitches

You can create only one default VPC network in one region and one default VSwitch for each zone in a VPC network. The following table lists the descriptions of default VPC networks and VSwitches:
Default VPC network Default VSwitch
You can create only one default VPC network in one region. You can create only one default VSwitch for each zone in a VPC network.
The subnet mask for a default VPC network has 16 bits, such as 172.31.0.0/16, which provides up to 65,536 internal IP addresses. The subnet mask for a default VSwitch has 20 bits, such as 172.16.0.0/20, which provides up to 4,096 internal IP addresses.
Default VPC networks do not consume the VPC quota allocated by Alibaba Cloud. Default VSwitches do not consume the VSwitch quota in a VPC network.
Default VPC networks are created by Alibaba Cloud. Manually created VPC networks are not default VPC networks. Default VSwitches are created by Alibaba Cloud. Manually created VSwitches are not default VSwitches.
The operations and specification limits of default VPC networks are the same as those of manually created VPC networks. The operations and specifications of default VSwitches are the same as those of manually created VSwitches.

Create cloud resources for default VPC networks and VSwitches

You can use default VPC networks and VSwitches when you create ECS, SLB, and ApsaraDB for RDS instances. For more information, see:
Note If you want to use default VPC networks and VSwitches when you create ECS instances, make sure that you have not created any VPC network in the region where you want to deploy the ECS instance.
Default VPC networks and VSwitches