When a virtual machine is powered on, VMware Workstation automatically assigns each of its virtual network adapters an Ethernet MAC address. MAC stands for media access control. A MAC address is the unique address assigned to each Ethernet network device.
The software guarantees that virtual machines are assigned unique MAC addresses within a given host system. However, the software does not guarantee that a given virtual machine is assigned the same MAC address every time it is powered on. In addition, VMware Workstation does its best, but cannot guarantee, to automatically assign unique MAC addresses for virtual machines running on multiple host systems.
If you want to guarantee that the same MAC address is assigned to a given virtual machine every time, or if you want to guarantee a unique MAC address for each virtual machine within a networked environment, you can assign the address manually instead of allowing VMware Workstation to assign it automatically.
To assign the same, unique MAC address to any virtual machine manually, use a text editor to add the following line to its configuration file (the .vmx file - on a Linux host, a virtual machine created with an earlier VMware product may have a configuration file with a .cfg extension):
ethernet0.address = 00:50:56:XX:YY:ZZ
where XX must be a valid hexadecimal number between 00h and 3Fh, and YY and ZZ must be valid hexadecimal numbers between 00h and FFh. Because VMware Workstation virtual machines do not support arbitrary MAC addresses, the above format must be used.
So long as you choose XX:YY:ZZ so it is unique among your hard-coded addresses (where XX is a valid hexadecimal number between 00h and 3Fh, and YY and ZZ are valid hexadecimal numbers between 00h and FFh), conflicts between the automatically assigned MAC addresses and the manually assigned ones should never occur.
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