Virtual machine (VM) A is connected to virtual switch A, and VM B is connected to virtual switch B. Which statement is true about the network traffic between A and B?
Traffic between VM A and VM B flows through the physical NIC.
Traffic between VM A and VM B stays within ESX Server.
VM A can communicate with VM B if they have same security policies.
VM A can communicate with VM B if they have same port group policies.
VMware Virtual Networking Concepts, page 5.
Network traffic cannot flow directly from one virtual switch to another virtual switch within the same host. Therefore an external switch is required.