In Microsoft's Virtual Machine, Virtual Server and VMWare Server you'll have to specify an IP address or obtain one automatically. When you do, the address is in line with whatever your environment receives. For example: If your network is on 192.168.x.x, then the virtual server will need to be as well. When I check the parallel virtual machine I'll receive an ip address of 10.211.x.x, but my environment is on 192.168.x.x. If I change the IP address on the virtual system, I am unable to connect to the network. Is this by design?
The address you receive in the VM is part of the un-routable 'private-network' address space used to allow Network Address Translation (NAT) to work correctly, if the Parallels VM was assigned a 192.168.x.x address it would become quickly confusing for everyone since most home/soho routers use the 192.168.x.x block of private addresses for their own NAT functionality (ie: you get one IP address from your phone/cable company, the Linksys/Netgear/Belkin device NATs your 2 or more computers to share the public IP). The parallels issued IP (10.211.x.x) is for the VM-to-host interface (ie: Windows to Mac OS), and is NATed out of existence before the packet hits your AirPort or Ethernet connection. If the Mac has a 192.168.x.x address for itself, Parallels Desktop will 'NAT-mangle' the 10.211.x.x packets to use the Mac's 192.168.x.x address on the way out, and then 'NAT-unmagle' them on the way back to the VM - the VM is never the wiser and thinks that the 10.211.x.x address is "real". If you want your VM to have a 'real' 192.168.x.x address, either to allow it to be addressed from the outside world, or to overcome port-forwarding issues, you can select "Bridged Networking" mode, then the VM can acquire a DHCP address of its own using a network adapter "MAC-alias" - then the Mac OS install might have 192.168.x.1 and the VM would have 192.168.x.2 - they could even address each other, such as using SSH to login to the Mac OS side from inside the Windows VM. Hope this is clear as mud for you. For more info look at the Linux HOWTO websites on Network Address Translation (NAT).
