MAC address differences

[HCHTech]

There was a question the other day about server IP reservations where the topic of MAC addresses came up. Because I have seen this issue on multiple occasions over the years, I suggested that the MAC address presented "to the network" might be 1 character different than the MAC address on the sticker.

I've seen this multiple times over the years, but it is not universal. It happens often enough, though that I always confirm the "to the network" address when setting reservations. Which makes me wonder....why is that? Do any of the network mavens here have an explanation for this difference and why it might occur in some cases and not in others?

 

[SAFCasper]

It usually happens when the device has multiple network interfaces. If you are referring to the thread I think your are, they mentioned VOIP phones which usually have 2 ethernet ports. I would guess the MAC on the sticker is correct for one of those ports and the other is slightly different.

Same logic for routers. Usually every port has a slightly different MAC but the sticker will only show one of them.