IPAutoconfigurationMask
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\ interface-name
Data type |
Range |
Default value |
|---|---|---|
REG_SZ |
Subnet mask (dotted decimal format) |
255.0.0.0 |
Description
Stores the subnet mask that the IP autoconfiguration feature assigns to the client.
Autoconfiguration allows TCP/IP to configure an interface even when it cannot locate a Dynamic Host Configuration Protocol (DHCP) server. If TCP/IP cannot locate DCHP server, it configures the interface by using IP addresses from the Microsoft reserved Class B network (169.254.0.0), subnet mask 255.255.0.0. During autoconfiguration, TCP/IP continues trying to locate a DHCP server, and it abandons autoconfiguration if it finds one.
IPAutoconfigurationMask also appears in the Parameters subkey, and its value applies, by default, to all interfaces. However, if this entry appears in any subkey of the Interfaces subkey, it takes precedence over the entry in the Parameters subkey when configuring the interface.
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Note
This entry is used only when IP autoconfiguration is enabled, that is, when the value of the IPAutoconfigurationEnabled entry is 1.
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Caution
Do not change the value of this entry. If you do, the IP address assigned to the interface might not be reliable.
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