XP clients disconnected from 2003 SBS machine intermittently

Ok will try to give as much detail as possible.

Recently users of a small SBS 2003 network have complained they are being disconnected from the network. They are working away fine on a database application which runs from the server and all of a sudden they get disconnected from both the application and from email when they browse through my network places and click on entire network and select their domain they receive "domainexample is not accessible you might not have permission to use this network resource. they cannot get to the server via unc or ip address. The SBS is set as their primary dns, it fails when they do an nslookup, they can browse the web fine as this goes through the firewall. The disconnect might only last a couple of seconds to a few minutes. The server is fully patched and there is no errors in een viewer to indicate any problems, I have run diagnostics on the network card and they all come back fine.

When the network went down I was unable to ping the firewall from the server however I was able to ping the firewall from a laptop connected into the same switch as the server ??! so the problem seems to point to the server but as event viewer is not displaying anything related and I have run a network analyzer which doesn't appear to highlight anything abnormal I'm stuck!

Any ideas
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Sid_FAsked:
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Shecky919Commented:
Hmmm, when the issue occurs have to tried having the server ping itself. Maybe a bad nic Driver or the Nic in the server going bad?
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Shecky919Commented:
Also, check the network cable and the port on the switch that the server is plugged into. Could be one of those.
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Sid_FAuthor Commented:
Yes have changed the port and can still ping the server from the client machines when the network goes down
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Rob WilliamsCommented:
>>"SBS is set as their primary dns"
Primary DNS? SBS should be the DHCP server, but it MUST be the only DNS server in the client configuration. The ISP cannot be added even as an alternate. If so, you will randomly have name resolution issues, and slow logons. The same goes for the server it must only point to itself for DNS. The ISP's DNS gets added as a forwarder in the DNS management console. If changes are needed on the server, do not so so manually, but re-run the CEICW which will configure the server as required.

Do you have 1 NIC or 2 on the server? Sounds like 1.
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Sid_FAuthor Commented:
Sorry yes client machines are configured for DHCP thats how they get their primary dns, we do configure the isp as a secondary dns as if the server goes down they still need access to the web. Logons are pretty normal with the isp as a secondary dns. We have not had any problems with this setup but I am always open to better ways of doing things.

Thanks
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Rob WilliamsCommented:
>>"Sorry yes client machines are configured for DHCP"
I assume with the SBS as the DHCP server and not the router?

>>"we do configure the isp as a secondary dns as if the server goes down they still need access to the web. "
You cannot do that. I appreciate why you have done it, but you cannot in a Windows domain. This is not an opinion but common Microsoft requirement. If you need redundancy, you need to add a second DC/DNS server. I have always wondered why internet is so important if you have lost access to the SBS which means DHCP, File access, authentication, and e-mail.  :-)
Try changing for a while and see if there is an improvement with your issue.
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Rob WilliamsCommented:
There is some good information regarding DNS in the following link. The issue with having the ISP as an alternate is Windows is it doesn't behave as it should. If it would always use the primary DNS server unless it was not present, there would be no issue. However, due to many reasons, Windows will often try the alternate and you either have slow name resolution, or none at all, which can result in the problems you are having. Using the ISP, though I don't believe as an alternate, is addressed in the following. The opening comment is also interesting; "over 70 percent of all support calls that come to Microsoft support services that start out as Active Directory or Exchange calls end up being DNS calls. "

10 DNS Errors That Will Kill Your Network
http://mcpmag.com/features/article.asp?editorialsid=413
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Sid_FAuthor Commented:
Ok, I have removed the secondary dns from dhcp and the clients are updated but the drop outs still occur.
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Rob WilliamsCommented:
When you next get a "drop out" try running NetDiag and see if it points to any non-physical connection issues.
http://www.lan-2-wan.com/Diag-FAQ.htm#q1
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Sid_FAuthor Commented:
Below is the output when the server has been running normally. I have connected the second network card since the last drop out.


C:\Documents and Settings\Administrator.mycompany>netdiag

.........................................

    Computer Name: SRVSBS
    DNS Host Name: SRVSBS.mycompany.local
    System info : Microsoft Windows Server 2003 (Build 3790)
    Processor : x86 Family 6 Model 15 Stepping 6, GenuineIntel
    List of installed hotfixes :
        KB924667-v2
        KB925398_WMP64
        KB925902
        KB926122
        KB927891
        KB929123
        KB930178
        KB931784
        KB931836
        KB932168
        KB933566
        KB933729
        KB933854
        KB935839
        KB935840
        KB935966
        KB936021
        KB936357
        KB936782
        KB938127-IE7
        KB938464
        KB941569
        KB942830
        KB942831
        KB943055
        KB943460
        KB943485
        KB944653
        KB945553
        KB946026
        KB948496
        KB948590
        KB948745
        KB949014
        KB950762
        KB950974
        KB951066
        KB951072-v2
        KB951698
        KB951746
        KB951748
        KB952954
        KB953838-IE7
        KB954211
        KB955069
        KB956390-IE7
        KB956391
        KB956803
        KB956841
        KB957095
        KB957097
        KB958644
        Q147222


Netcard queries test . . . . . . . : Passed



Per interface results:

    Adapter : Server Local Area Connection

        Netcard queries test . . . : Passed

        Host Name. . . . . . . . . : SRVSBS
        IP Address . . . . . . . . : 192.168.16.200
        Subnet Mask. . . . . . . . : 255.255.255.0
        Default Gateway. . . . . . : 192.168.16.4
        Primary WINS Server. . . . : 192.168.16.200
        Dns Servers. . . . . . . . : 192.168.16.200


        AutoConfiguration results. . . . . . : Passed

        Default gateway test . . . : Passed

        NetBT name test. . . . . . : Passed
        [WARNING] At least one of the <00> 'WorkStation Service', <03> 'Messenge
r Service', <20> 'WINS' names is missing.

        WINS service test. . . . . : Passed

    Adapter : Network Connection

        Netcard queries test . . . : Passed

        Host Name. . . . . . . . . : SRVSBS
        IP Address . . . . . . . . : 192.168.16.201
        Subnet Mask. . . . . . . . : 255.255.255.0
        Default Gateway. . . . . . : 192.168.16.4
        Primary WINS Server. . . . : 192.168.16.200
        Dns Servers. . . . . . . . : 192.168.16.200


        AutoConfiguration results. . . . . . : Passed

        Default gateway test . . . : Passed

        NetBT name test. . . . . . : Passed
            No names have been found.

        WINS service test. . . . . : Passed


Global results:


Domain membership test . . . . . . : Passed


NetBT transports test. . . . . . . : Passed
    List of NetBt transports currently configured:
        NetBT_Tcpip_{D17744B7-97B0-4741-8D3B-FD90E2092632}
    1 NetBt transport currently configured.


Autonet address test . . . . . . . : Passed


IP loopback ping test. . . . . . . : Passed


Default gateway test . . . . . . . : Passed


NetBT name test. . . . . . . . . . : Passed
    [WARNING] You don't have a single interface with the <00> 'WorkStation Servi
ce', <03> 'Messenger Service', <20> 'WINS' names defined.


Winsock test . . . . . . . . . . . : Passed


DNS test . . . . . . . . . . . . . : Passed
    PASS - All the DNS entries for DC are registered on DNS server '192.168.16.2
00' and other DCs also have some of the names registered.


Redir and Browser test . . . . . . : Passed
    List of NetBt transports currently bound to the Redir
        NetBT_Tcpip_{D17744B7-97B0-4741-8D3B-FD90E2092632}
    The redir is bound to 1 NetBt transport.

    List of NetBt transports currently bound to the browser
        NetBT_Tcpip_{D17744B7-97B0-4741-8D3B-FD90E2092632}
    The browser is bound to 1 NetBt transport.


DC discovery test. . . . . . . . . : Passed


DC list test . . . . . . . . . . . : Passed


Trust relationship test. . . . . . : Skipped


Kerberos test. . . . . . . . . . . : Passed


LDAP test. . . . . . . . . . . . . : Passed


Bindings test. . . . . . . . . . . : Passed


WAN configuration test . . . . . . : Skipped
    No active remote access connections.


Modem diagnostics test . . . . . . : Passed

IP Security test . . . . . . . . . : Skipped

    Note: run "netsh ipsec dynamic show /?" for more detailed information


The command completed successfully

C:\Documents and Settings\Administrator.mycompany>Event String: The dynamic r
egistration of the DNS record



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Sid_FAuthor Commented:
The drop outs happen several times a day at different times. As mentioned there is nothing in event viewer on the server.
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Rob WilliamsCommented:
That report looks clean, but I was hopping you could run it on a problematic PC when the connection was lost to the server.

>>"I have connected the second network card since the last drop out."
This is not a good idea. SBS ha a specific configuration for using 2 NIC's and they must be in 2 different subnets, one external and the other internal, and it sits between the client and Internet as a firewall. Having 2 NICs in this way can cause DNS issues.
Be careful when disabling the second NIC.
If you reconfigure the original LAN NIC it will "break" networking, DNS, Sharepoint access, remote access and more. The "configure server IP" MUST be used when making changes to the LAN NIC.
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Sid_FAuthor Commented:
It would seem the database application is generating massive amounts of netbios traffic due to the way the application executes
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Sid_FAuthor Commented:
We never managed to resolve this issue and no longer deal with this site. Request to close the question
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