MAC addresses are used to restrict packet transmission to the intended recipient. Each virtual network adapter in a virtual machine is assigned its own unique MAC address.

The following options are for MAC address generation:

VMware OUI allocation - default allocation

Prefix-based allocation

Range-based allocation

After the MAC address is generated, it does not change unless the virtual machine has MAC address collision with another registered virtual machine. The MAC address is saved in the configuration file of the virtual machine. All MAC addresses that have been assigned to network adapters of running and suspended virtual machines on a given physical machine are tracked.

If you use invalid prefix- or range-based allocation values, an error is logged in the vpxd.log file and vCenter Server will not allocate MAC addresses during a virtual machine provisioning.