Question: Is there a way to find out, using Win2008 R2 Hyper-V manager or a command-line tool, the externally-accessible IP Address(es) of Windows XP Hyper-V guests? 

I'd like to be able to connect to my guests by IP address via Remote Desktop (for cases where name resolution is not working properly) but without combing through the DHCP server it's been challenging to know which IP address corresponds to which host. 

Any ideas?

Assigning static IPs to each guest is possible but is something I'd like to avoid.

Answer: 
Why not just use the Hyper-V Manager to open the VM's Console? It works remotely if you have Remote Management enabled in the Firewall Settings, and you don't have to do any look-ups in the DHCP Server. Otherwise, no, Hyper-V does not track it's VMs IPs, just their MAC addresses.
You could use a script to get the information from WMI (from [technet](http://msdn.microsoft.com/en-us/library/aa394595(VS.85).aspx)):

...determine the IP address of a computer?

Use the Win32\_NetworkAdapterConfiguration class and check the value of the IPAddress property. This is returned as an array, so use a For-Each loop to get the value.
strComputer = "."

```

Set objWMIService = GetObject( _ 
    "winmgmts:\\" & strComputer & "\root\cimv2")
Set IPConfigSet = objWMIService.ExecQuery _
    ("Select IPAddress from Win32_NetworkAdapterConfiguration ")

For Each IPConfig in IPConfigSet
    If Not IsNull(IPConfig.IPAddress) Then 
        For i=LBound(IPConfig.IPAddress) _
            to UBound(IPConfig.IPAddress)
                WScript.Echo IPConfig.IPAddress(i)
        Next
    End If
Next
```

Sadly that's code for the local machine, and you'd need to tweak it according to [this article](http://msdn.microsoft.com/en-us/library/aa389290(v=VS.85).aspx) to connect to the remote WMI.

It might just be easier to have each machine write its IP address to a text file on a network share when it starts up.

Or you could query the DHCP server directly for the information (if it's MS, [Can I query DHCP server for getting mapping of MAC to IP address (I have admin rights)?](https://serverfault.com/questions/110864/can-i-query-dhcp-server-for-getting-mapping-of-mac-to-ip-address-i-have-admin-ri) should work)