Subnet¶
A subnet is a unique CIDR block with a range of IP addresses in a VPC. All resources in a VPC must be deployed on subnets.
By default, all instances in different subnets of the same VPC can communicate with each other. If you have a VPC with two subnets in it, they can communicate with each other by default.
After a subnet is created, its CIDR block cannot be modified. Subnets in the same VPC cannot overlap.
A subnet mask can be between the netmask of its VPC CIDR block and /29 netmask. If a VPC CIDR block is 10.0.0.0/16, its subnet mask can be between 16 and 29.
For example, if the CIDR block of VPC-A is 10.0.0.0/16, you can specify 10.0.0.0/24 for subnet A01, 10.0.1.0/24 for subnet A02, and 10.0.3.0/24 for subnet A03.
Note
By default, you can create a maximum of 100 subnets in each region. If this cannot meet your service requirements, request a quota increase by referring to What Is a Quota?