The switch's administrative IP subnet mask. The switch may automatically discover a value for this object using the BootStrap protocol (BOOTP). The object value is also duplicated in the MIB-II ipAddrTable. The following applies to switches operating with firmware version smaller than 6.00: When VLANs are present, The switch may be configured with up to 4 administrative IP subnet masks, one per VLAN. This object, in this case, configures the subnet mask for the first VLAN. See the object vlanTable for how to configure the other subnet masks. Assigning multiple VLAN subnet masks is only necessary if the VLANs in use represent separate physical IP subnets. A write to this value will take effect immediately. The default value is 0.0.0.0, or no subnet mask.