Can't find DC

Discussion in 'Server Networking' started by CarlosAntenna, Aug 29, 2005.

  1. I have a network with only one server and about 25 workstations. All
    workstations connect to a shared network drive for data and some
    applications (drive S:). One of the newest workstations loses
    communication with the S: drive nearly every day, but not the same time, and
    not tied to any event that can be replicated. I tried disconnecting the
    mapped S: drive and then reconnecting. It says it cannot find the DC to
    verify my login to the S: drive. But, I can PING the IP of the DC.
    Rebooting the PC is the only fix. What is causing this???

    Win 2000 Server, sp4 fully patched
    Win XP, sp2 fully patched

    And wouldn't you know it... It's the president's machine that is doing this.
    He leaves everything open on his desktop. Multiple documents in several
    different applications. When he has to reboot, he whines and complains that
    it is going to take him hours to get back to where he was. And I'm the guy
    who has to listen to it.

    -- Carlos --
    CarlosAntenna, Aug 29, 2005
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  2. Hi,

    few questions and things to look at.

    If I understand this PC is member of Windows 2000 domain? How is DNS set up
    on client PC? Where does DNS point to?
    Are there any errors or other events that might explain what is going on in
    Event log (specially in System and Application logs). You should also check
    the logs on domain controller.
    Miha Pihler [MVP], Aug 29, 2005
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  3. Check the nic card setting for speed and make sure they match those of the
    switch the pc is plugged into. Manually set and don't leave at 'auto'. So
    that would be 100mb full duplex or 100mb half duplex, etc for both switch
    port and nic.

    Reason I recommend this is what you describe is intermittent network
    failure. When autonegociate between the nic and switch doesn't work quite
    right there are crc errors generated which require packet resends and/or loss
    of network connectivity.

    If its a managed switch you can look at the port stats to verify these errors.
    Joshua Bolton, Aug 29, 2005
  4. Thanks Miha,

    Yes it is a member of a Win2000 domain
    PC gets DNS from DHCP; it points to our ISP's DNS servers.

    Event log entries follow:

    In the Server System Event Log

    Source: NETLOGON
    Dynamic registration or deregistration of one or more DNS records
    failed because no DNS servers are available.

    In the Workstation System Event Log

    Source: NETLOGON
    No Domain Controller is available for domain FLATPLATE due to the
    There are currently no logon servers available to service the
    logon request. .
    Make sure that the computer is connected to the network and try
    again. If the problem persists, please contact your domain

    I also took Joshua's advice and switched the NIC from Auto to 100/full
    duplex so as not to get tripped up over the negotiation.

    I hope these log entries mean more to you than they do to me.

    -- Carlos --
    CarlosAntenna, Aug 30, 2005
  5. Thanks Josh,

    The switch is not managed. I did change the NIC on the PC to 100mb/full
    duplex to avoid negotiation. Maybe that will do the trick. See also my
    response to Miha, above.


    -- Carlos --

    CarlosAntenna, Aug 30, 2005
  6. OK. Here is the problem. Client should _not_ point to your ISP DNS but to
    your Active Directory DNS which is usually your Active Directory server.

    Clients use DNS to locate your Active Directory and other services in
    domain. If you point your clients to your ISP they will fail to find domain
    controllers since your ISP's DNS servers don't know anything about your
    internal domain.

    What you should do is point all your clients, servers (even domain
    controllers) to Active Directory DNS. Once you do this, configure DNS
    forwarders on your Active Directory DNS server to point to your ISP (you do
    this in DNS MMC on DNS server). This will enable your clients to resolve
    internet addresses.

    So the requests would go like this. If your internal DNS name is
    then any request for "" would go to your internal DNS server and
    no further since the server knows "everything" about "". If the
    client need to go to e.g. it passes the request to Active
    Directory DNS and since it doesn't know anything about it will
    pass on the request to your ISP. Once it gets the response back it will
    forward it to the client.

    I hope this helps,
    Miha Pihler [MVP], Aug 30, 2005
  7. Thanks again Mike,

    When I go to the DNS server and look at the "forwarders" tab, things are
    greyed out and it says "Forwarders are not available because this is a root
    server". What now?

    The DHCP server is giving out the same DNS servers to all clients. Why are
    other workstations not experiencing the same problem?


    -- Carlos --
    Carlos Antenna, Aug 31, 2005
  8. CarlosAntenna

    Bill Grant Guest

    Simply delete the dot at the top of the tree. While the dot is there,
    the DNS is a root server and thinks it is the centre of the universe! It
    won't forward to a higher authority.
    Bill Grant, Aug 31, 2005
  9. Thanks Bill,

    The dot was under "forward lookup zones". I deleted it, but it still thinks
    it's a root server.

    I restarted the service and nothing changed. Will I also need to reboot the

    -- Carlos --
    Carlos Antenna, Aug 31, 2005
  10. CarlosAntenna

    Todd J Heron Guest

    Reboot the server.

    Todd J Heron, MCSE
    Windows Server 2003/2000/NT; CCA
    This posting is provided "as is" with no warranties and confers no rights

    Thanks Bill,

    The dot was under "forward lookup zones". I deleted it, but it still thinks
    it's a root server.

    I restarted the service and nothing changed. Will I also need to reboot the

    -- Carlos --
    Todd J Heron, Aug 31, 2005
  11. Thanks Todd,

    I rebooted and got everything set up as everyone in this thread has
    suggested. Now only time will tell whether the presidents problems have
    been fixed.

    I will post back after two or three days and let everyone know how it turned

    -- Carlos --
    CarlosAntenna, Aug 31, 2005
  12. It has been nearly three days now and everything is still working. I
    consider it a huge success.

    MANY THANKS to all who contributed to this thread, especially Mike.

    CarlosAntenna, Sep 2, 2005
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