Event ID 31 — NLB Host Configuration

Updated: November 25, 2009

Applies To: Windows Server 2008 R2

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Hosts in a Network Load Balancing (NLB) cluster are configured to load balance network traffic. Host configuration is set by using NLB Manager, and if it is not configured properly, the NLB cluster may not function correctly.

 

Event Details

Product: Windows Operating System
ID: 31
Source: Microsoft-Windows-NLB
Version: 6.1
Symbolic Name: MSG_ERROR_CL_NET_MASK
Message: NLB cluster [%2]: The NLB driver failed to initialize because the cluster network mask %3 is invalid. Please check that the network mask is specified in a valid format.

Resolve

Check that the cluster network mask is valid

If the Network Load Balancing (NLB) driver fails to initialize because the cluster network mask is not in a valid format, you should check that the network mask is specified in a valid format.

When you are using NLB Manager, you must be a member of the Administrators group on the host that you are configuring, or you must have been delegated the appropriate authority. If you are configuring a cluster or host by running NLB Manager from a computer that is not part of the cluster, you do not have to be a member of the Administrators group on that computer.

To check that the cluster subnet mask is correctly specified:

  1. Click Start, click Administrative Tools, and then click Network Load Balancing Manager. You can also open NLB Manager by typing Nlbmgr at a command prompt.
  2. If NLB Manager does not already list the cluster, connect to the cluster.
  3. Right-click the cluster, and then click Cluster Properties.
  4. Click the Cluster Parameters tab, and, in Subnet mask, verify that the subnet mask is correctly specified. The mask should be entered in standard Internet dotted notation (for example, 255.255.255.0).

 

Verify

When you are using nlb.exe, you must be a member of the Administrators group on the host that you are configuring, or you must have been delegated the appropriate authority. If you are configuring a cluster or host by running nlb.exe from a computer that is not part of the cluster, you do not have to be a member of the Administrators group on that computer.

To verify that all Network Load Balancing (NLB) hosts are in the converged state:

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type nlb.exe query, which displays the current cluster state and the list of host priorities for the current hosts of the cluster.
  3. Confirm that all hosts display converged as their current state.

Related Management Information

NLB Host Configuration

NLB Cluster

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