DsIsNTDSOnline function

[This function is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions. Beginning with Windows Vista, use Volume Shadow Copy Service (VSS) instead.]

The DsIsNTDSOnline function determines if Active Directory Domain Services are online on the specified server.


  _In_  LPCTSTR szServerName,
  _Out_ BOOL    *pfNTDSOnline


szServerName [in]

Pointer to a null-terminated string that contains the name of the server to test. Preceding backslashes are optional. The server must be the same computer that this function is called from. The server name cannot contain any underscore (_) characters. An example of a server name is "\\server1".

pfNTDSOnline [out]

Pointer to BOOL value that receives the result. Receives TRUE if the directory service is online or FALSE if the directory service is offline.

Return value

Returns S_OK if the function is successful or an error code otherwise. The following list lists possible error codes.


The caller does not have the proper access privileges to call this function. The DsSetAuthIdentity function can be used to set the credentials to use for the backup and restore functions.


The server in szServerName cannot be found, is not a domain controller, or szServerName is not formatted correctly. This value is defined in Ntdsbmsg.h.


The DsIsNTDSOnline function is being called remotely or the server in szServerName is not a domain controller.


Call this function before calling any of the directory backup or restore functions. The directory must be online in order to perform a backup. The directory must by offline to perform a restore.

This function can only be called from a domain controller that is also the target server specified in szServerName. This function cannot be called remotely.


Minimum supported client
Windows Vista
Minimum supported server
Windows Server 2008
Unicode and ANSI names
DsIsNTDSOnlineW (Unicode) and DsIsNTDSOnlineA (ANSI)

See also


Directory Backup Functions

Backing Up and Restoring an Active Directory Server