Hyper V Networking issues, one VM reports IP of but responds on the assigned address?

Posted on 2009-04-28
Last Modified: 2013-11-11
I have an instance of Hyper V running on Server 2008.  The server is running Enterprise but has no other functions other than hosting the VM's on it.  I am pretty new to VM's in general and really new to Hyper V.

This is what I am seeing:
On the Hyper V host, 2 physical NIC's, 1 Virtual:
Local Area Connection - Broadcom - Access to Local and Internet  - IP is set to XXX.144 IPV4 only <-connected to switch, 1 Gbps connection

Local Area Connection 2 - Broadcom #2 - 'connectivity' is not described - only protocol is the MS Virtual Switch Protocol - 1Gbps connection (this is 'really' the physical nic on the switch I think)

Local Area Connection 4 - Broadcom #4 Virtual Network - Access to Local Only - IP is XXX.145 IPV4 only - 10Gbps

On the Hyper V settings I have 1 External connection to Broadcom #2 and no other networks (no Internal Only or Private VM network connection)

My intention was to have the host server be on one NIC (.144) and the VM's bound to the second NIC (.145) and that's the one the virtual NIC uses - it seems that's how it is happening, correct?

I don't think I need another virtual connection to allow the VM's to communicate with each other do I?  That is the 10Gbps virtual adapter correct?

I have some basic services running as VMs (5 total). They all have static addresses, one is a backup DC (AD integrated) and is running DHCP for the whole subnet (.0/24) as well (but the scope gives clients a primary DNS server that is a standalone box - DHCP keeps working even though:

This backup DC and DHCP server (XXX.157) always shows an IP of as well as a subnet of (the Gateway is correct).  It is pointing to the primary DNS server/DC (non VM, xxx.184) for DNS and itself secondarily.

I can ping 157 though and get a response back and *some* machines know it by FQDN but others don't.  The primary DNS/DC knows it by FQDN.

If I go into Advanced on the network settings on 157 and remove the IP address (the static 157 address sits there underneath) and go back to the main tab 157 is in there with the proper subnet... I give it 5 minutes and come back and its back to

Checking on the Hyper V VM's and their settings they all use the same virtual NIC and have static addresses like 157 does but they all work... none of the address problems.

On 157 I am getting 4015 and 4011 errors in the DNS logs, basically it is unable to update or sync with the AD/DNS of the domain it is in.  We also transfer zones with another domain and although 157 asks this separate domain to transfer it gets refused, going to the other domain to enable the transfer fails, it cannot find the FQDN of 157.

It's all very strange to me... does anyone have any ideas?

Question by:IELTechServices
    LVL 59

    Accepted Solution

    Just to make sure I'm understanding you correctly you are setting the IPs in the Hyper-V VM not on the host server. I would uninstall the NIC from the Hyper-V settings page then reinstall a Legacy Adapter.

    Author Comment

    That's half the solution, or at least the right track - I did some fiddling and figured it out (not why it was that way in the first place, however - but it's working now)

    Yah, that is correct. Each of the VMs has an IP address. The VM's are 2008 and 2003 servers and use the Integrated Services Setup Disk to get the correct NIC driver.  Only this one installation has this problem.  I ended up using Hyper V manager to connect (instead of TermServ) to the VM in question and 'removed' the NIC.  Rebooted, came back up with a IP.  I did the Integration disk again, rebooted and it came back up fine.  IP is holding.

    The Event Viewer was giving me errors based on the fact that even though I could ping the server and connect via TS from another machine, DNS still thought there was no IP ( .  Those errors cleared up right away and DNS/AD started doing it's thing.

    Still doesn't explain the zero'd out IP address (a new VM I just installed on the same host came up fine)...

    Thanks for the reply.


    Author Closing Comment

    I should have started with the obvious, NIC is giving you trouble (even though its virtual) - yank it out and put it back in... ;)

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