Can't find DC

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 --

 

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.

 

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.

 

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
following:
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
administrator.

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.

Thanks,
-- Carlos --

 

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.

Thanks,

-- Carlos --

errors.

 

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 domain.com
then any request for "domain.com" would go to your internal DNS server and
no further since the server knows "everything" about "domain.com". If the
client need to go to e.g. www.google.com it passes the request to Active
Directory DNS and since it doesn't know anything about google.com 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,

 

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?

thanks,

-- Carlos --

 

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.

 

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
server?

-- Carlos --

 

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
server?

-- Carlos --

 

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
out.

-- Carlos --

 

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.

--Carlos--