WSCWriteNameSpaceOrder32 function

The WSCWriteNameSpaceOrder32 function changes the order of available Windows Sockets (Winsock) 2 namespace providers in a 32-bit catalog. The order of the namespace providers determines the priority of the namespace when enumerated or queried for name resolution.

Note  This call is a strictly 32-bit version of WSCWriteNameSpaceOrder for use on 64-bit platforms. It is provided to allow 64-bit processes to reorder the 32-bit namespace provider catalog.


int WSPAPI WSCWriteNameSpaceOrder32(
  _In_ LPGUID lpProviderId,
  _In_ DWORD  dwNumberOfEntries


lpProviderId [in]

An array of NSProviderId elements as found in the WSANAMESPACE_INFO structure. The order of the NSProviderId elements is the new priority ordering for the namespace providers.

dwNumberOfEntries [in]

The number of elements in the NSProviderId array.

Return value

The function returns ERROR_SUCCESS (zero) if the routine is successful. Otherwise, it returns a specific error code.

Error codeMeaning

The NSProviderId array is not fully contained within process address space.


Input parameters were invalid, no action was taken.


A nonrecoverable error occurred. This error is returned under several conditions including the following: the Winsock registry could not be opened, the user lacks the administrative privileges required to write to the Winsock registry, or another application is currently writing to the namespace provider catalog.


A system call that should never fail has failed.


The function is called by another thread or process.


Insufficient memory was available to perform the operation.


The function may return any registry error code.



Namespace providers are installed on 64-bit platforms in a 32-bit namespace provider catalog using the WSCInstallNameSpace32 function. The order in which namespace providers in a 32-bit catalog are initially installed governs the default order in which they are enumerated through WSCEnumNameSpaceProviders32. More importantly, this order also governs the order in which namespace providers are considered when a client requests name resolution. On 64-bit platforms, the WSCWriteNameSpaceOrder32 function is provided to allow 64-bit processes to change the order of namespace providers in the 32-bit namespace provider catalog. The order of namespace providers in the native catalog can be changed using the WSCWriteNameSpaceOrder function.

The current namespace provider catalog is stored in the registry under the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\Current Control Set\Services\Winsock2\Parameters\NameSpace_Catalog5

A client request for name resolution uses the WSALookupServiceBegin, WSALookupServiceNext, and WSALookupServiceEnd routines. The dwNameSpace member of the WSAQUERYSET structure passed to WSALookupServiceBegin is set to the identifier of a single namespace (NS_DNS, for example) in which to constrain the search, or NS_ALL to include all namespaces. If multiple namespace providers support a specific namespace (for example, NS_DNS), then the results from all namespace providers that match the requested dwNameSpace are returned unless the lpNSProviderId member is set to a specific namespace provider. The results from all namespace providers is returned if NS_ALL is specified for the dwNameSpace member. The order that the results are returned depends on the namespace provider order in the catalog.

The Windows SDK includes an application called SpOrder.exe that allows the catalog of installed namespace providers to be displayed. Winsock 2 includes the ws2_32.DLL on 64-bit platforms that exports the WSCWriteNameSpaceOrder32 function for reordering namespace providers in the 32-bit namespace provider catalog. This interface can be imported by linking with WS2_32.lib. For computers running on Windows XP with Service Pack 2 (SP2) and Windows Server 2003 with Service Pack 1 (SP1) and later, the netsh.exe winsock show catalog command will display both the protocol and namespace providers installed. The native 64-bit catalog is displayed first followed by the 32-bit provider catalogs (denoted with a 32 after their name).

WSCWriteNameSpaceOrder32 can only be called by a user logged on as a member of the Administrators group. If WSCWriteNameSpaceOrder32 is called by a user that is not a member of the Administrators group, the function call will fail and WSANO_RECOVERY is returned in the lpErrno parameter.

For computers running on Windows Vista and Windows Vista, this function can also fail because of user account control (UAC). If an application that contains this function is executed by a user logged on as a member of the Administrators group other than the Administrator, this call will fail unless the application has been marked in the manifest file with a requestedExecutionLevel set to requireAdministrator. If the application on Windows Vista and Windows Vista lacks this setting in the manifest file used to build the executable file, a user logged on as a member of the Administrators group other than the Administrator must then be executing the application in an enhanced shell as the Administrator (RunAs administrator) for this function to succeed.

The following list describes scenarios in which the WSCWriteNameSpaceOrder32 function could fail:

  • The dwNumberOfEntries parameter is not equal to the number of registered namespace providers.
  • The NSProviderId array contains an invalid namespace provider identifier.
  • The NSProviderId array does not contain all valid namespace provider identifiers exactly one time.
  • The function is not able to access the registry for some reason (insufficient user permissions, for example).
  • Another process, or thread, is currently calling the function.


Minimum supported client

Windows Vista, Windows XP Professional x64 Edition [desktop apps only]

Minimum supported server

Windows Server 2008, Windows Server 2003 x64 Edition [desktop apps only]







See also