If no virtual private cloud (VPC) is created in a region, you can specify the system to create a default VPC and a default vSwitch when you create an Elastic Compute Service (ECS), Server Load Balancer (SLB), or ApsaraDB RDS instance. After the instance is created, a default VPC and a default vSwitch are created.
Features of default VPCs and default vSwitches
|Feature||Default VPC||Default vSwitch|
|Uniqueness||You can create only one default VPC in a region.||You can create only one default vSwitch for each zone in a VPC.|
|Subnet mask length and IP addresses||The subnet mask for a default VPC is 16 bits in length. For example, the 172.31.0.0/16 CIDR block provides up to 65,536 private IP addresses.||The subnet mask for a default vSwitch is 20 bits in length. For example, the 172.16.0.0/20 CIDR block provides up to 4,096 private IP addresses.|
|Quotas||Default VPCs do not consume the VPC quotas allocated to your Alibaba Cloud account.||Default vSwitches do not consume the vSwitch quotas for a VPC.|
|Creation method||Default VPCs are automatically created by Alibaba Cloud. Manually created VPCs are custom VPCs.||Default vSwitches are automatically created by Alibaba Cloud. Manually created vSwitches are custom vSwitches.|
|Operations and specifications||