You use Juniper Apstra to enable a new VXLAN virtual network.

According to the Juniper documentation1, a VXLAN virtual network is a collection of Layer 2 forwarding domains that span multiple racks in a fabric. A VXLAN virtual network requires a name and a VXLAN network identifier (VNI), which is a 24-bit number that identifies the virtual network. The VNI can be either explicitly assigned or auto-assigned from a resource pool. A VXLAN virtual network can also have Layer 3 connectivity, which enables routing between different VNIs within a routing zone. A routing zone is an L3 domain that isolates the IP traffic of different tenants. A routing zone can have one or more VNIs associated with it. To enable Layer 3 connectivity, a VXLAN virtual network needs an IP subnet, which is a range of IP addresses that can be assigned to the hosts in the virtual network. The IP subnet can be either explicitly assigned or auto-assigned from a resource pool. Therefore, the correct answer is A and C. IP subnet and VXLAN VNI are two components that would be automatically derived when enabling a new VXLAN virtual network using Juniper Apstra. References: Virtual Networks | Apstra 4.1 | Juniper Networks