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  • NetBT Duplicate name event

    We are periodically receiving the following System Event. This is 2 node file cluster

    After running nbtstat -n, I do not see any duplicate names (results output).

    Source: NetBT
    ID: 4319

    A duplicate name has been detected on the TCP network. The IP address of the machine that sent the message is in the data. Use nbtstat -n in a command window to see which name is in the Conflict state.

    **************************RESULTS***************** **


    Public LAN 10.x.x.x:
    Node IpAddress: [10.0.0.13] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    FS1 <00> UNIQUE Registered
    MGADM <00> GROUP Registered
    FS1 <20> UNIQUE Registered
    MGADM <1E> GROUP Registered

    Public LAN 172.x.x.x:
    Node IpAddress: [172.16.20.48] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    FS1 <00> UNIQUE Registered
    MGADM <00> GROUP Registered
    FS1 <20> UNIQUE Registered
    MGADM <1E> GROUP Registered

    Private Heartbeat:
    Node IpAddress: [10.1.1.1] Scope Id: []

    No names in cache

    \Device\NetBt_If1:
    Node IpAddress: [10.0.1.40] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    MGA05 <00> UNIQUE Registered
    FS <20> UNIQUE Registered
    FS <00> UNIQUE Registered
    MGA05 <20> UNIQUE Registered

    \Device\NetBt_If2:
    Node IpAddress: [10.0.0.4] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    FSCLUSTER <20> UNIQUE Registered
    FSCLUSTER <00> UNIQUE Registered

    \Device\NetBt_If3:
    Node IpAddress: [172.16.20.51] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    MGA05 <00> UNIQUE Registered
    FS <20> UNIQUE Registered
    FS <00> UNIQUE Registered
    MGA05 <20> UNIQUE Registered

    \Device\NetBt_If4:
    Node IpAddress: [10.0.1.20] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    MGA05 <00> UNIQUE Registered
    FS <20> UNIQUE Registered
    FS <00> UNIQUE Registered
    MGA05 <20> UNIQUE Registered

    \Device\NetBt_If5:
    Node IpAddress: [172.16.20.50] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    MGA05 <00> UNIQUE Registered
    FS <20> UNIQUE Registered
    FS <00> UNIQUE Registered
    MGA05 <20> UNIQUE Registered

    \Device\NetBt_If6:
    Node IpAddress: [10.0.0.5] Scope Id: []

    NetBIOS Local Name Table

    Name Type Status
    ---------------------------------------------
    MGA05 <00> UNIQUE Registered
    FS <20> UNIQUE Registered
    FS <00> UNIQUE Registered
    MGA05 <20> UNIQUE Registered

    **************************END RESULTS*******************

    I cannot bring down the 2 node cluster to use ICMP to test if there is name using any of its IPs. I have also used tools on the subnet and did not find any dup names using the IP addresses. Sniffing packets with Ethereal did not show any duplicate names either.

    Any ideas of other ways or tools that can be help or the possible issue. This has happened a couple of times during the week.

    Thanks
    Verbalh
    CCNA, MCSE, MCP, Network+, CNA, A+

  • #2
    Re: NetBT Duplicate name event

    looks like, at girst glance, both nodes in the cluster are registering themselves as the netbt name..
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    Comment


    • #3
      Re: NetBT Duplicate name event

      Hi,

      What windows version is it and are you using any WINS servers at all?
      Caesar's cipher - 3

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      SFX JNRS FC U6 MNGR

      Comment


      • #4
        Re: NetBT Duplicate name event

        This often happens with clusters, NLB, or multihomed machines as each NIC or node registers the same NetBIOS name. IMHO opinion this event message can be ignored.

        You could try disabling NetBIOS over TCP on the clusterd NIC if you really want to make the event messages go away.

        Comment


        • #5
          Re: NetBT Duplicate name event

          joeqwerty,

          This suggestion makes sense but if I disable Netbios/TCIP on one of the two NICs which are on separate subnets

          Lets say NIC1 uses 172.16.x.x
          NIC2 uses 10.0.x.x

          If I disable NIC1 name resolution will resolve since NIC2 is enabled but if for instance NIC2 completely failed then since we do not have Netbios/TCPIP enabled on NIC1 then name resolution would not work. This is the only conflict I have wit that configuration. Let me know your thoughts

          thx
          Verbalh
          CCNA, MCSE, MCP, Network+, CNA, A+

          Comment


          • #6
            Re: NetBT Duplicate name event

            DNS name resolution would continue to work normally as it does not rely on NetBIOS.

            I don't think it's a big deal to leave it as it is. I see these event messages occasionally in our TS NLB farm and it doesn't cause any problems so I just ignore the messages.

            I do have NetBIOS over TCP disabled on the TS NIC that NLB is bound to, but since the other NIC has NetBIOS over TCP enabled, NetBIOS name resolution works fine. Only one NIC should register with DNS and register it's NetBIOS name, not both.

            Comment


            • #7
              Re: NetBT Duplicate name event

              joeqwerty,

              Yes, I am aware with 2000 (AD) clients are not dependent on Netbios. You only need it if you have Netbios enabled applications on your network or legacy clients (ie 95/98 ). My concern was just the lost of a NIC and possibly not being to resolve a name if the other NIC is not registering.

              I have not seen it cause a problem either and have been ignoring but wanted to some insight since I could not determine if there was a system on the network with those IPs. I will probably just disable on of the NICs and keep on the other.
              Last edited by biggles77; 14th June 2009, 07:09. Reason: Fix smilie
              Verbalh
              CCNA, MCSE, MCP, Network+, CNA, A+

              Comment


              • #8
                Re: NetBT Duplicate name event

                Right, I get what you're saying. IMO, the cluster NIC should be registered using the cluster name not the host name, so if you disable NetBIOS on the clustered NIC all should work fine. If the cluster NIC goes down then all traffic should go to the other host(s) in the cluster. This should have no effect or bearing on the non-clustered NIC, which should be registerd in DNS and should register it's NetBIOS name.

                This is all based on my understanding of NLB. On our NLB NIC we disable NetBIOS and DNS registration.

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