I ran into a problem recently where virtual machines I created from a template were fighting over the same IP address. Each of them would be assigned the same IP address from my DHCP server, despite the fact that each VM created from my standard template had a unique Mac address. I had a hard time finding the culprit, so I figured I would write a post about it. In my case, I am using Proxmox, though the root-cause is not specific to any virtualization package. My virtual machines were all running Ubuntu 18.04, though this may impact other distributions too. The root cause ended up being due to something called a “machine-id”. Read on to find out how I solved this.