In the early 90's a friend of mine got a box of 10 HP cards with all the same MAC address. ----- Original Message ----- From: "Graham Wooden" <graham@g-rock.net> To: nanog@nanog.org Sent: Sunday, 2 January, 2011 4:33:46 PM Subject: The tale of a single MAC Hi there, I encountered an interesting issue today and I found it so bizarre so I thought I would share it. I brought online a spare server to help offload some of the recent VMs that I have been deploying. Around the same time this new machine (we¹ll call it Server-B) came online, another machine which has been online for about a year now stopped responding to our monitoring (and we¹ll name this Server-A). I logged into the switch and saw that the machine that stopped responding was in the same VLAN as this newly deployed, and then quickly noticed that Server-A¹s MAC address was now on Server-B¹s switch port. ³What the ...² was my initial response.