IFPCEENLBCluster::Mask property

Applies to: desktop apps only

The Mask property gets the subnet mask for the virtual IP address of the Network Load Balancing (NLB) cluster.

This property is read-only.


HRESULT get_Mask(
  BSTR *pbstrMask
' Data type: String

Property Mask( _
  ByVal pbstrMask As BSTR _
) As String

Property value

String that specifies the subnet mask for the virtual IP address of the NLB cluster.

Error codes

This property method returns S_OK if the call is successful; otherwise, it returns an error code.


This property is read-only. Its default value is an empty string. The subnet mask for the virtual IP address of the NLB cluster can be modified by calling the SetVIPAndMask method.

The subnet mask is specified in this property as a string in dotted-decimal format. Its binary value should consist of a series of ones followed by a series of zeros. These series of bits separate the IP address specified in the VIP property into two parts. The first part specifies a network address, and the bits of the second part are reserved for all of the possible host addresses in the network segment. The combination of the virtual IP address and the subnet mask must specify the same network address as do the combinations of the dedicated IP addresses and subnet masks of the array member network adapters attached to the network.

The subnet mask typically consists of zero, one, two, or three binary octets that are represented in dotted-decimal format by the decimal number 255 and one binary octet that contains a series of ones (which may be empty) followed by a series of zeros and is represented by one of the following decimal numbers:

  • 254
  • 252
  • 248
  • 240
  • 224
  • 192
  • 128
  • 0


Minimum supported client

Windows Vista

Minimum supported server

Windows Server 2008 R2, Windows Server 2008 with SP2 (64-bit only)


Forefront Threat Management Gateway (TMG) 2010





See also




Build date: 7/12/2010