Sever 2012 Essentials DNS Issues

Posted on 2014-08-22
Last Modified: 2016-06-13
We recently migrated from SBS 2003 to Server 2012 Essentials.

In the days of SBS 2003, it was handling DHCP and DNS. The router/firewall is now handling DHCP.

We are seeing some strange and unexplainable DNS issues.
The server is showing incorrect DNS records for a lot of the computers. I will delete them and they show back up at some point. To make it more confusing (or maybe less), I THINK it is showing the SAME ip address each time and I recognize them from before.

For example, I know at one point we gave Computer 1 a static ip address of (but have since changed it back to DHCP). The server will show - but the REAL ip address of the computer is

DHCP is NOT enabled on the server.
DHCP is enabled on the router.
NO Static IP addresses are assigned on the router.
The old server is NOT connected.

I know there is more info you are going to need but I'm not  sure what it is.
Question by:rheide
    LVL 41

    Expert Comment

    Why is the router doing DHCP? Is the router set to hand out only your server as the only DNS server? It is usually better to have your Windows server acting as your DHCP server.
    LVL 24

    Expert Comment

    I agree that Windows should do the DHCP in a domain environment.. with Active Directory and such.  What type of router?  Does it know to let Windows DNS do dynamic updates?

    Author Comment

    Essentials comes out of the box expecting the router to handle DHCP. I'm not against changing that but that is why it was setup this way.
    LVL 41

    Expert Comment

    Weird. I have never used Windows Server Essentials, and that seems very strange. I suggest configuring DHCP on the server, turn it off on the router and see how things go.
    LVL 20

    Expert Comment

    by:Daniel McAllister
    Some salient points here:
     1) It does not matter which device is DHCP server, so long as it is configuring hosts the correct way.
     2) In an AD environment, that means that the AD server is the primary (if only 1 server, then only) DNS server
     3) A lot of low-end routers can't do this
     4) In an AD environment, the DHCP server is also supposed to notify the DNS server when it assigns an address -- and again, low-end routers often cannot do this.

    If your DNS server is setting 192.168.0.x as the IP of System "x" then figuring out how the setting got there probably means going to System "x" and verifying:
     - what is the real IP there, and
     - how did it get that address (DOS: ipconfig /all will show this)

    You may find:
     - The DHCP server is somehow using that "old" address and the values are indeed correct
     - The DHCP server isn't actually your router, after all.
     - There may be another system/device on your network causing the havoc! :^)

    I would be remiss if I didn't agree with some of the other experts here:
     - In an AD world, the AD server is your best bet for both DNS and DHCP services

    To echo that point, in many of my Linux or otherwise "mixed" environments, my AD server is a VM -- usually on a 10 or 20GB VM drive -- and those 3 functions (AD, DNS, & DHCP) are the only things that VM does...

    I hope this helps...

    LVL 25

    Expert Comment

    Essentials is intended to function in a small-office environment in which the router handles DHCP. In fact, the Essentials server can operate just fine with a dynamic IP address. If it detects a DHCP server on the network, it will lease an address and go from there. The idea is to minimize the amount of manual configuration that must be performed. If everything works as advertised, you simply take the server out of the box, plug it and your client machines into the network, and go. (OK, it's not quite that simple, but it's close.)

    It works this way because of the Windows Server LAN Configuration service, which gets installed on all clients that join a Windows Server Essentials domain. This service is supposed to detect the Essentials server whenever the client is connected to the network. If it detects the server, it resolves its IP address and configures the client to use that address as its only DNS server. If it doesn't detect the server, the client uses whatever DNS servers it gets from DHCP.

    I'm not a huge fan of this, because it can be pretty confusing if you've never seen it before, but I see the point behind it - and when it works, it's kinda nifty. When it doesn't work, it's one more thing you have to troubleshoot. I'd start by making sure the Windows Server LAN Configuration service exists on all of your clients and is running.

    You do, of course, have the option of giving the Essentials server a static IP address and using it as the DHCP server. If you do so, you don't need to worry about the Windows Server LAN Configuration service any more. Instructions for running DHCP on the server are given here.

    Quite a bit more about the Windows Server LAN Configuration service can be found here.

    Accepted Solution

    FYI - I replaced our firewall and it solved all problems! Crazy.

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