Ask Different is a question and answer site for power users of Apple hardware and software. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My MacBook gets a different IP every time I resume from sleep even though I have set up an IP reservation based on the MAC address. This works fine for the Windows and Linux clients. I also have the same problem on a corporate Cisco LAN.

Any ideas?

share|improve this question
Are you sure you are entering the correct MAC address? Is this wireless or wired? – Gerry Sep 10 '12 at 14:09
Hi Gerry, The netgear router fills that in for you. If I try to add it again the router confirms the MAC address is a duplicate. Also this is the same process used with the Linux and Windows clients. – user28853 Sep 10 '12 at 14:51
Can you verify the MAC address that gets filled in with the actual MAC address on your adapter? You should make sure you are looking at the right adapter, the wired adapter has a different MAC address than the wireless one. – Gerry Sep 10 '12 at 14:56
How can this be an OS X problem at all? IP addresses are assigned by the router, the OS shouldn't matter at all. – patrix Sep 21 '12 at 19:12

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.