How to keep the ethernet interface up when removing the cable?

Question

On 10.6 I notice that if the ethernet cable is unplugged, it will not bring the interface up. As a result, I cannot test my server without the interface attached. For instance, if en0 is 192.168.2.10 and a web server is running, the local DNS translates the web servers domain to 192.168.2.10, I cannot reach my own web server as there is no route to host. This is probably energy conservation issue, but it makes life rather unpleasant, because if the interface goes down when there is a cable problem, I also get all sorts of internal problems because of the missing host (e.g. a virtual machine looking for a DNS server on 192.168.2.10 which is suddenly unreachable).
This was not the case with 10.5 Server and I think the last time I had this kind of behaviour was with my NeXT cube where the en0 interface would not come up without a cable attached to it and a switch.
So, is there a way I can force OS X 10.6 to bring up the en0 interface on 192.168.2.10 no matter what?

Answer 1

I have made my DNS reachable at all times by using 127.0.0.1 for the "DNS to use" in my ethernet settings in System Preferences.
Using localhost is no go, as I am running three separate IP-addresses (three en intrerfaces) on my single RJ-45. This way, I can let several web sites for different domains listen to different IP-addresses. Furthermore, I can make sure on the router's NAT that for instance only one of those gets the port 443 traffic and that one does not get port 80 and the other way around.
The solution I have now is a cable attached to a switch attached to nothing else. But it is inelegant, I'd rather know how to make the interfaces come up regardless what is attached to the RJ-45.