Here,s why:
vcn_id: This attribute specifies the ID of the Virtual Cloud Network (VCN) to which the subnet belongs. While it relates to the subnet,s location, it doesn,t define the subnet,s specific address range.
subnet_id: This attribute refers to the unique identifier of the subnet itself, assigned after its creation. It doesn,t define the subnet,s address range either.
availability_domain: This attribute specifies the availability domain (AD) where the subnet will be created. While relevant for resource placement, it doesn,t define the CIDR block.
cidr_block: This attribute explicitly defines the network address range allocated to the subnet using CIDR notation (e.g., "10.0.1.0/24").