If you are like me and build and destroy things constantly or just like doing things in ways you probably are not supposed to here is a quick tip.
I was destroying a vCD environment the other day but I wanted to save some templates I created with vCD. Instead of exporting and re-importing or using some intelligent method. I used vCenter to clone the VM to another place. While I was using this machine I cloned it off a few times for some tests.
Then I noticed some network wackiness. A ping would work for a a little while then go away and come back. First thought was I messed something up in the networking on these new hosts. After searching and searching and checking for switching loops. I finally found the machine had a manually coded MAC address. So I had 5 VM’s on the network with the same MAC address. This obviously caused some issues.
To fix it I migrated the machines to VMXNET3, and removed the old NIC because I needed to do that anyway. You could also change the MAC back to automatic. I would guess you would need to powerdown for this, but I didn’t test this out yet.