Data type Range Default value
REG_MULTI_SZ (A space-delimited list of dotted decimal subnet masks.) (There is no default value for this entry. The value is configured by DHCP.)


Specifies the subnet mask associated with a DHCP option.

The subnet mask stored in the value of this entry is not used for routing. DHCP just uses this entry to test and build the actual subnet mask which is stored in the value of DhcpSubnetMask.

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This entry is associated with a DHCP option. Configuration data for DHCP options is stored in each HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dhcp\Parameters\Options\ <Option#> subkey. The path to this entry is stored in the value of RegLocation in the associated <Option#> subkey.

To find the DHCP option associated with this entry, use Regedit.exe. From the Edit menu, click Find, and enter the following text: SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\?\DhcpSubnetMaskOpt and select only the Data checkbox.

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The DHCP client service adds this entry to the registry when the service is enabled. It is maintained for internal use by the DHCP client service. Do not delete this entry or change its value.

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