Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

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

I've read and re-read the manual and scoured ServerFault and other sites. I just don't get it.

I've got Virtualbox running on a Mac OS X host, with two Windows Server 2008 R2 guests. Both have a single NIC running in Bridged mode connected to eth0 on the host. Both have internet access, both can ping my gateway (a separate router connected to the internet). But they can't see each other.

When I try to ping them I get destination host unreachable. I've tried manually entering an ARP entry for the MAC address of each host in the other, to no avail.

What am I doing wrong? What am I missing?

share|improve this question
up vote 0 down vote accepted

Forget it. I've found the problem. VirtualBox has given them the same MAC address. I have no idea why this has happened, but whatever. My goal here is to do some Windows Server testing, not figure out the intricacies of VirtualBox.

share|improve this answer
Ok so I figured out why this happened now, total PEBKAC moment! To save time, I built the first machine then sysprepped it and exported it as an appliance. Re-imported it, and of course it had the same MAC address. Just refreshed it on one of the guests and it was all good. – Matt Jul 3 '11 at 11:58

Your Answer


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

Not the answer you're looking for? Browse other questions tagged or ask your own question.