Which virtual switch should a VM connect with for use as a network-attached device on the physical network?

Connecting a virtual machine (VM) to an external virtual switch is the correct choice for enabling it to communicate as a network-attached device on the physical network. An external virtual switch connects directly to the physical network adapters on the host machine, allowing VMs to access external networks, including the internet and other network resources, as if they were physical machines on that network.

This capability is essential for VMs that need to participate in the same network as other devices, share files, or communicate with servers. It enables the VM to obtain an IP address from a DHCP server on the physical network or to be reachable by other devices on the network.

The other options serve different purposes. An internal virtual switch allows communication between VMs on the same host and the host itself but does not provide access to external networks. A private virtual switch limits communication to only the VMs that are connected to it, completely isolating them from the host and any external networks. A bulletin board switch is not a standard type of virtual switch and does not apply in this context. Thus, connecting the VM to an external virtual switch is the most appropriate choice for network connectivity.